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Sample records for te ute pulse

  1. Magnetic resonance imaging of the normal pituitary gland using ultrashort TE (UTE) pulse sequences (REV 1.0)

    International Nuclear Information System (INIS)

    Portman, Olivia; Flemming, Stephen; Cox, Jeremy P.D.; Johnston, Desmond G.; Bydder, Graeme M.

    2008-01-01

    The purpose of this study was to examine the normal pituitary gland in male subjects with ultrashort echo time (TE) pulse sequences, describe its appearance and measure its signal intensity before and after contrast enhancement. Eleven male volunteers (mean age 57.1 years; range 36-81 years) were examined with a fat-suppressed ultrashort TE (= 0.08 ms) pulse sequence. The studies were repeated after the administration of intravenous gadodiamide. The MR scans were examined for gland morphology and signal intensity before and after enhancement. Endocrinological evaluation included baseline pituitary function tests and a glucagon stimulatory test to assess pituitary cortisol and growth hormone reserve. High signal intensity was observed in the anterior pituitary relative to the brain in nine of the 11 subjects. These regions involved the whole of the anterior pituitary in three subjects, were localised to one side in two examples and were seen inferiorly in three subjects. Signal intensities relative to the brain increased with age, with a peak around the sixth or seventh decade and decreasing thereafter. Overall, the pituitary function tests were considered to be within normal limits and did not correlate with pituitary gland signal intensity. The anterior pituitary shows increased signal intensity in normal subjects when examined with T 1 -weighted ultrashort TE pulse sequences. The cause of this increased intensity is unknown, but fibrosis and iron deposition are possible candidates. The variation in signal intensity with age followed the temporal pattern of iron content observed at post mortem. No relationship with endocrine status was observed. (orig.)

  2. Magnetic resonance imaging of the normal pituitary gland using ultrashort TE (UTE) pulse sequences (REV 1.0)

    Energy Technology Data Exchange (ETDEWEB)

    Portman, Olivia; Flemming, Stephen; Cox, Jeremy P.D.; Johnston, Desmond G. [Imperial College Faculty of Medicine, St Mary' s Hospital, Endocrinology and Metabolic Medicine, London (United Kingdom); Bydder, Graeme M. [University of California, San Diego, Department of Radiology, San Diego, CA (United States)

    2008-03-15

    The purpose of this study was to examine the normal pituitary gland in male subjects with ultrashort echo time (TE) pulse sequences, describe its appearance and measure its signal intensity before and after contrast enhancement. Eleven male volunteers (mean age 57.1 years; range 36-81 years) were examined with a fat-suppressed ultrashort TE (= 0.08 ms) pulse sequence. The studies were repeated after the administration of intravenous gadodiamide. The MR scans were examined for gland morphology and signal intensity before and after enhancement. Endocrinological evaluation included baseline pituitary function tests and a glucagon stimulatory test to assess pituitary cortisol and growth hormone reserve. High signal intensity was observed in the anterior pituitary relative to the brain in nine of the 11 subjects. These regions involved the whole of the anterior pituitary in three subjects, were localised to one side in two examples and were seen inferiorly in three subjects. Signal intensities relative to the brain increased with age, with a peak around the sixth or seventh decade and decreasing thereafter. Overall, the pituitary function tests were considered to be within normal limits and did not correlate with pituitary gland signal intensity. The anterior pituitary shows increased signal intensity in normal subjects when examined with T{sub 1}-weighted ultrashort TE pulse sequences. The cause of this increased intensity is unknown, but fibrosis and iron deposition are possible candidates. The variation in signal intensity with age followed the temporal pattern of iron content observed at post mortem. No relationship with endocrine status was observed. (orig.)

  3. Magnetic resonance imaging (MRI) of articular cartilage of the knee using ultrashort echo time (uTE) sequences with spiral acquisition

    International Nuclear Information System (INIS)

    Goto, Hajimu; Fujii, Masahiko; Iwama, Yuki; Aoyama, Nobukazu; Ohno, Yoshiharu; Sugimura, Kazuro

    2012-01-01

    The objective of this study was to evaluate the sensitivity of ultrashort echo time (uTE) sequence for visualisation of calcified deep layers of articular cartilage. MRI with a uTE sequence was performed on five healthy volunteers. Signals from the calcified deep layers of the articular knee cartilage were evaluated on uTE subtraction images and computed tomography images. The calcified deep layers of the articular cartilage changed from having a low to a high signal when imaged with a uTE sequence. The reported uTE sequence was effective in imaging the deep layers of the knee cartilage.

  4. The effect of excitation and preparation pulses on nonslice selective 2D UTE bicomponent analysis of bound and free water in cortical bone at 3T

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shihong [Department of Radiology, University of California, San Diego, California 92103-8226 (United States); Department of Radiology, Hua Dong Hospital, Fudan University, Shanghai 200040 (China); Yancheng Medical College, Jiangsu (China); The First People' s Hospital of Yancheng City, Jiangsu 224005 (China); Chang, Eric Y.; Chung, Christine B. [VA San Diego Healthcare System, San Diego, California 92161 and Department of Radiology, University of California, San Diego, California 92103-8226 (United States); Bae, Won C.; Du, Jiang, E-mail: jiangdu@ucsd.edu [Department of Radiology, University of California, San Diego, California 92103-8226 (United States); Hua, Yanqing [Department of Radiology, Hua Dong Hospital, Fudan University, Shanghai 200040 (China); Zhou, Yi [The First People' s Hospital of Yancheng City, Jiangsu 224005 (China)

    2014-02-15

    Purpose: The purpose of this study was to investigate the effect of excitation, fat saturation, long T2 saturation, and adiabatic inversion pulses on ultrashort echo time (UTE) imaging with bicomponent analysis of bound and free water in cortical bone for potential applications in osteoporosis. Methods: Six bovine cortical bones and six human tibial midshaft samples were harvested for this study. Each bone sample was imaged with eight sequences using 2D UTE imaging at 3T with half and hard excitation pulses, without and with fat saturation, long T2 saturation, and adiabatic inversion recovery (IR) preparation pulses. Single- and bicomponent signal models were utilized to calculate the T2{sup *}s and/or relative fractions of short and long T2{sup *}s. Results: For all bone samples UTE T2{sup *} signal decay showed bicomponent behavior. A higher short T2{sup *} fraction was observed on UTE images with hard pulse excitation compared with half pulse excitation (75.6% vs 68.8% in bovine bone, 79.9% vs 73.2% in human bone). Fat saturation pulses slightly reduced the short T2{sup *} fraction relative to regular UTE sequences (5.0% and 2.0% reduction, respectively, with half and hard excitation pulses for bovine bone, 6.3% and 8.2% reduction, respectively, with half and hard excitation pulses for human bone). Long T2 saturation pulses significantly reduced the long T2{sup *} fraction relative to regular UTE sequence (18.9% and 17.2% reduction, respectively, with half and hard excitation pulses for bovine bone, 26.4% and 27.7% reduction, respectively, with half and hard excitation pulses for human bone). With IR-UTE preparation the long T2{sup *} components were significantly reduced relative to regular UTE sequence (75.3% and 66.4% reduction, respectively, with half and hard excitation pulses for bovine bone, 87.7% and 90.3% reduction, respectively, with half and hard excitation pulses for human bone). Conclusions: Bound and free water T2{sup *}s and relative fractions can

  5. The effect of excitation and preparation pulses on nonslice selective 2D UTE bicomponent analysis of bound and free water in cortical bone at 3T

    International Nuclear Information System (INIS)

    Li, Shihong; Chang, Eric Y.; Chung, Christine B.; Bae, Won C.; Du, Jiang; Hua, Yanqing; Zhou, Yi

    2014-01-01

    Purpose: The purpose of this study was to investigate the effect of excitation, fat saturation, long T2 saturation, and adiabatic inversion pulses on ultrashort echo time (UTE) imaging with bicomponent analysis of bound and free water in cortical bone for potential applications in osteoporosis. Methods: Six bovine cortical bones and six human tibial midshaft samples were harvested for this study. Each bone sample was imaged with eight sequences using 2D UTE imaging at 3T with half and hard excitation pulses, without and with fat saturation, long T2 saturation, and adiabatic inversion recovery (IR) preparation pulses. Single- and bicomponent signal models were utilized to calculate the T2 * s and/or relative fractions of short and long T2 * s. Results: For all bone samples UTE T2 * signal decay showed bicomponent behavior. A higher short T2 * fraction was observed on UTE images with hard pulse excitation compared with half pulse excitation (75.6% vs 68.8% in bovine bone, 79.9% vs 73.2% in human bone). Fat saturation pulses slightly reduced the short T2 * fraction relative to regular UTE sequences (5.0% and 2.0% reduction, respectively, with half and hard excitation pulses for bovine bone, 6.3% and 8.2% reduction, respectively, with half and hard excitation pulses for human bone). Long T2 saturation pulses significantly reduced the long T2 * fraction relative to regular UTE sequence (18.9% and 17.2% reduction, respectively, with half and hard excitation pulses for bovine bone, 26.4% and 27.7% reduction, respectively, with half and hard excitation pulses for human bone). With IR-UTE preparation the long T2 * components were significantly reduced relative to regular UTE sequence (75.3% and 66.4% reduction, respectively, with half and hard excitation pulses for bovine bone, 87.7% and 90.3% reduction, respectively, with half and hard excitation pulses for human bone). Conclusions: Bound and free water T2 * s and relative fractions can be assessed using UTE bicomponent

  6. Syntheses and crystal structures of BaAgTbS{sub 3}, BaCuGdTe{sub 3}, BaCuTbTe{sub 3}, BaAgTbTe{sub 3}, and CsAgUTe{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, Jai; Beard, Jessica C.; Ibers, James A. [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113 (United States); Mesbah, Adel [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113 (United States); ICSM-UMR 5257 CNRS/CEA/UM2/ENSCM, Bat 426, BP 17171, 30207 Bagnols/Ceze (France)

    2015-06-15

    Five new quaternary chalcogenides of the 1113 family, namely BaAgTbS{sub 3}, BaCuGdTe{sub 3}, BaCuTbTe{sub 3}, BaAgTbTe{sub 3}, and CsAgUTe{sub 3}, were synthesized by the reactions of the elements at 1173-1273 K. For CsAgUTe{sub 3} CsCl flux was used. Their crystal structures were determined by single-crystal X-ray diffraction studies. The sulfide BaAgTbS{sub 3} crystallizes in the BaAgErS{sub 3} structure type in the monoclinic space group C{sup 3},{sub 2h}-C2/m, whereas the tellurides BaCuGdTe{sub 3}, BaCuTbTe{sub 3}, BaAgTbTe{sub 3}, and CsAgUTe{sub 3} crystallize in the KCuZrS{sub 3} structure type in the orthorhombic space group D{sup 1},{sub 2}{sup 7},{sub h}-Cmcm. The BaAgTbS{sub 3} structure consists of edge-sharing [TbS{sub 6}{sup 9-}] octahedra and [AgS{sub 5}{sup 9-}] trigonal pyramids. The connectivity of these polyhedra creates channels that are occupied by Ba atoms. The telluride structure features {sup 2}{sub ∞}[MLnTe{sub 3}{sup 2-}] layers for BaCuGdTe{sub 3}, BaCuTbTe{sub 3}, BaAgTbTe{sub 3}, and {sup 2}{sub ∞}[AgUTe{sub 3}{sup 1-}] layers for CsAgUTe{sub 3}. These layers comprise [MTe{sub 4}] tetrahedra and [LnTe{sub 6}] or [UTe{sub 6}] octahedra. Ba or Cs atoms separate these layers. As there are no short Q..Q (Q = S or Te) interactions these compounds achieve charge balance as Ba{sup 2+}M{sup +}Ln{sup 3+}(Q{sup 2-}){sub 3} (Q = S and Te) and Cs{sup +}Ag{sup +}U{sup 4+}(Te{sup 2-}){sub 3}. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. SU-E-J-224: Using UTE and T1 Weighted Spin Echo Pulse Sequences for MR-Only Treatment Planning; Phantom Study

    Energy Technology Data Exchange (ETDEWEB)

    Yu, H; Fatemi, A [Sunnybrook Health Sciences Centre, Toronto, Ontario (Canada); Sahgal, A [University of Toronto, Toronto, ON (Canada)

    2015-06-15

    Purpose: Investigating a new approach in MRI based treatment planning using the combination of (Ultrashort Echo Time) UTE and T1 weighted spin echo pulse sequences to delineate air, bone and water (soft tissues) in generating pseudo CT images comparable with CT. Methods: A gel phantom containing chicken bones, ping pang balls filled with distilled water and air bubbles, was made. It scanned with MRI using UTE and 2D T1W SE pulse sequences with (in plane resolution= 0.53mm, slice thickness= 2 mm) and CT with (in plane resolution= 0.5 mm and slice thickness= 0.75mm) as a ground truth for geometrical accuracy. The UTE and T1W SE images were registered with CT using mutual information registration algorithm provided by Philips Pinnacle treatment planning system. The phantom boundaries were detected using Canny edge detection algorithm for CT, and MR images. The bone, air bubbles and water in ping pong balls were segmented from CT images using threshold 300HU, - 950HU and 0HU, respectively. These tissue inserts were automatically segmented from combined UTE and T1W SE images using edge detection and relative intensity histograms of the phantom. The obtained segmentations of air, bone and water inserts were evaluated with those obtained from CT. Results: Bone and air can be clearly differentiated in UTE images comparable to CT. Combining UTE and T1W SE images successfully segmented the air, bone and water. The maximum segmentation differences from combine MRI images (UTE and T1W SE) and CT are within 1.3 mm, 1.1mm for bone, air, respectively. The geometric distortion of UTE sequence is small less than 1 pixel (0.53 mm) of MR image resolution. Conclusion: Our approach indicates that MRI can be used solely for treatment planning and its quality is comparable with CT.

  8. Generation of brain pseudo-CTs using an undersampled, single-acquisition UTE-mDixon pulse sequence and unsupervised clustering

    International Nuclear Information System (INIS)

    Su, Kuan-Hao; Hu, Lingzhi; Traughber, Melanie; Stehning, Christian; Helle, Michael; Qian, Pengjiang; Thompson, Cheryl L.; Pereira, Gisele C.; Traughber, Bryan J.; Jordan, David W.; Herrmann, Karin A.; Muzic, Raymond F.

    2015-01-01

    Purpose: MR-based pseudo-CT has an important role in MR-based radiation therapy planning and PET attenuation correction. The purpose of this study is to establish a clinically feasible approach, including image acquisition, correction, and CT formation, for pseudo-CT generation of the brain using a single-acquisition, undersampled ultrashort echo time (UTE)-mDixon pulse sequence. Methods: Nine patients were recruited for this study. For each patient, a 190-s, undersampled, single acquisition UTE-mDixon sequence of the brain was acquired (TE = 0.1, 1.5, and 2.8 ms). A novel method of retrospective trajectory correction of the free induction decay (FID) signal was performed based on point-spread functions of three external MR markers. Two-point Dixon images were reconstructed using the first and second echo data (TE = 1.5 and 2.8 ms). R2 ∗ images (1/T2 ∗ ) were then estimated and were used to provide bone information. Three image features, i.e., Dixon-fat, Dixon-water, and R2 ∗ , were used for unsupervised clustering. Five tissue clusters, i.e., air, brain, fat, fluid, and bone, were estimated using the fuzzy c-means (FCM) algorithm. A two-step, automatic tissue-assignment approach was proposed and designed according to the prior information of the given feature space. Pseudo-CTs were generated by a voxelwise linear combination of the membership functions of the FCM. A low-dose CT was acquired for each patient and was used as the gold standard for comparison. Results: The contrast and sharpness of the FID images were improved after trajectory correction was applied. The mean of the estimated trajectory delay was 0.774 μs (max: 1.350 μs; min: 0.180 μs). The FCM-estimated centroids of different tissue types showed a distinguishable pattern for different tissues, and significant differences were found between the centroid locations of different tissue types. Pseudo-CT can provide additional skull detail and has low bias and absolute error of estimated CT

  9. Ute Mountain Ute Tribe Community-Scale Solar Feasibility Study

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, Jim [Parametrix; Knight, Tawnie [Ute Mountain Ute Tribe

    2014-01-30

    Parametrix Inc. conducted a feasibility study for the Ute Mountain Ute Tribe to determine whether or not a community-scale solar farm would be feasible for the community. The important part of the study was to find where the best fit for the solar farm could be. In the end, a 3MW community-scale solar farm was found best fit with the location of two hayfield sites.

  10. Ga–Ge–Te amorphous thin films fabricated by pulsed laser deposition

    International Nuclear Information System (INIS)

    Němec, P.; Nazabal, V.; Dussauze, M.; Ma, H.-L.; Bouyrie, Y.; Zhang, X.-H.

    2013-01-01

    UV pulsed laser deposition was employed for the fabrication of amorphous Ga–Ge–Te thin films. The local structure of the bulk glasses as well as corresponding thin films was studied using Raman scattering spectroscopy; the main structural motifs were found to be [GeTe 4 ], eventually [GaTe 4 ] corner-sharing tetrahedra and disordered Te chains. Optical functions of the films (refractive index, extinction coefficient) were characterized by variable angle spectroscopic ellipsometry. Photostability experiments showed all Ga–Ge–Te laser deposited films to be stable against 1550 nm laser irradiation in an as-deposited state. In an annealed state, the most photostable composition seems to be Ga 10 Ge 15 Te 75 . This particular composition was further studied from the point of view of thermal stability and stability against ageing in as-deposited state. - Highlights: ► Pulsed laser deposition was used for fabrication of amorphous Ga–Ge–Te thin films. ► GeTe 4 , eventually GaTe 4 tetrahedra and disordered Te chains form the film structure. ► Optical functions of Ge–Ga–Te films were characterized by spectroscopic ellipsometry. ► All as-deposited Ga–Ge–Te thin films are stable against 1550 nm irradiation. ► In annealed state, the most photostable composition seems to be Ga 10 Ge 15 Te 75

  11. MR-based attenuation correction in brain PET based on UTE sequences

    Energy Technology Data Exchange (ETDEWEB)

    Cabello, Jorge; Nekolla, Stephan G; Ziegler, Sibylle I [Department of Nuclear Medicine, Klinikum rechts der Isar, Technische Universität München (Germany)

    2014-07-29

    Attenuation correction (AC) in brain PET/MR has recently emerged as one of the challenging tasks in the PET/MR field. It has been shown that to ignore the attenuation produced by bone can lead to errors ranging from 5-30% in regions close to bone structures. Since the information provided by the MR signal is not directly related to tissue attenuation, alternative methods have to be developed. Signal from bone tissue is difficult to measure given its short transverse relaxation time (T2). Ultrashort-echo time (UTE) pulse sequences were developed to measure signal from tissues with short T2. A combination of two consecutive UTE echoes has been used in several works to measure signal from bone tissue. The first echo is able to measure signal from bone tissue in addition to soft tissue, while the second echo contains most of the soft tissue contained in the first echo but not bone. In this work we extract the attenuation information from the difference between the logarithm of two images obtained after applying two consecutive UTE pulse sequences using the mMR scanner (Siemens Healthcare). Subsequently, image processing techniques are applied to reduce the noise and extract air cavities within the head. The resulting image is converted to linear attenuation coefficients, generating what is known as µ-map, to be used during reconstruction. For comparison purposes PET/CT scans of the same patients were acquired prior to the PET/MR scan. Additional µ-maps obtained for comparison were extracted from a Dixon sequence (used in clinical routine) and an additional µ-map calculated by the scanner based on UTE pulse sequences. Preliminary quantitative results measured in the cerebellum, using the value obtained with CT-based AC as reference, show differences of 34% without AC, 13% using the Dixon-based and UTE-based provided by the scanner, and 0.8% with the AC strategy presented here.

  12. Functional imaging of murine hearts using accelerated self-gated UTE cine MRI.

    Science.gov (United States)

    Motaal, Abdallah G; Noorman, Nils; de Graaf, Wolter L; Hoerr, Verena; Florack, Luc M J; Nicolay, Klaas; Strijkers, Gustav J

    2015-01-01

    We introduce a fast protocol for ultra-short echo time (UTE) Cine magnetic resonance imaging (MRI) of the beating murine heart. The sequence involves a self-gated UTE with golden-angle radial acquisition and compressed sensing reconstruction. The self-gated acquisition is performed asynchronously with the heartbeat, resulting in a randomly undersampled kt-space that facilitates compressed sensing reconstruction. The sequence was tested in 4 healthy rats and 4 rats with chronic myocardial infarction, approximately 2 months after surgery. As a control, a non-accelerated self-gated multi-slice FLASH sequence with an echo time (TE) of 2.76 ms, 4.5 signal averages, a matrix of 192 × 192, and an acquisition time of 2 min 34 s per slice was used to obtain Cine MRI with 15 frames per heartbeat. Non-accelerated UTE MRI was performed with TE = 0.29 ms, a reconstruction matrix of 192 × 192, and an acquisition time of 3 min 47 s per slice for 3.5 averages. Accelerated imaging with 2×, 4× and 5× undersampled kt-space data was performed with 1 min, 30 and 15 s acquisitions, respectively. UTE Cine images up to 5× undersampled kt-space data could be successfully reconstructed using a compressed sensing algorithm. In contrast to the FLASH Cine images, flow artifacts in the UTE images were nearly absent due to the short echo time, simplifying segmentation of the left ventricular (LV) lumen. LV functional parameters derived from the control and the accelerated Cine movies were statistically identical.

  13. Microstructure evolution in pulsed laser deposited epitaxial Ge-Sb-Te chalcogenide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Ulrich; Lotnyk, Andriy, E-mail: andriy.lotnyk@iom-leipzig.de; Thelander, Erik; Rauschenbach, Bernd

    2016-08-15

    The thin film deposition and structure of highly oriented telluride compounds is of particular interest for phase-change applications in next-generation non-volatile memory such as heterostructure designs, as well as for the investigation of novel optical, thermoelectric and ferroelectric properties in layered telluride compounds. In this work, epitaxial Ge-Sb-Te thin films were successfully produced by pulsed laser deposition on silicon with and without amorphous SiO{sub x} interlayer at elevated process temperatures from a Ge{sub 2}Sb{sub 2}Te{sub 5} target. Aberration-corrected high-resolution scanning transmission electron microscopy (STEM) imaging reveals a distinct interface configuration of the trigonal phase connected by a quasi van der Waals gap (vacancy) to the Sb/Te-passivated single crystalline Si substrate, yet also an intermediate textured growth regime in which the substrate symmetry is only weakly coupled to the thin film orientation, as well as strong deviation of composition at high deposition temperatures. Textured growth of Ge-Sb-Te thin film was also observed on SiO{sub x}/Si substrate with no evidence of an intermediate Sb/Te surface layer on top of an SiO{sub x} layer. In addition, particular defect structures formed by local reorganization of the stacking sequence across the vacancy gap are observed and appear to be intrinsic to these van der Waals-layered compounds. Theoretical image simulations of preferred stacking sequences can be matched to individual building blocks in the Ge-Sb-Te grain. - Highlights: • Atomic-resolution Cs-corrected STEM imaging of PLD deposited Ge-Sb-Te thin films. • Changing of overall composition with increasing deposition temperature. • Direct imaging of surface passivation Sb/Te layer at the Ge-Sb-Te/Si(111) interface. • The Sb/Te passivation layer is not a prerequisite for highly oriented growth of Ge-Sb-Te thin films.

  14. Correction of echo shift in reconstruction processing for ultra-short TE pulse sequence

    International Nuclear Information System (INIS)

    Takizawa, Masahiro; Ootsuka, Takehiro; Abe, Takayuki; Takahashi, Tetsuhiko

    2010-01-01

    An ultra-short echo time (TE) pulse sequence is composed of a radial sampling that acquires echo signals radially in the K-space and a half-echo acquisition that acquires only half of the echo signal. The shift in the position of the echo signal (echo shift) caused by the timing errors in the gradient magnetic field pulses affects the image quality in the radial sampling with the half-echo acquisition. To improve image quality, we have developed a signal correction algorithm that detects and eliminates this echo shift during reconstruction by performing a pre-scan within 10 seconds. The results showed that image quality is improved under oblique and/or off-centering conditions that frequently cause image distortion due to hardware error. In conclusion, we have developed a robust ultra-short TE pulse sequence that allows wide latitude in the scan parameters, including oblique and off-centering conditions. (author)

  15. Transport properties and specific heat of UTe and USb

    International Nuclear Information System (INIS)

    Ochiai, A.; Suzuki, Y.; Shikama, T.; Suzuki, K.; Hotta, E.; Haga, Y.; Suzuki, T.

    1994-01-01

    Uranium monochalcogenides and monopnictides crystallize in the NaCl-type structure and exhibit ferromagnetic and antiferromagnetic order, respectively. These series reveal interesting properties such as Kondo behavior of UTe. However, such interesting properties are much sample dependent. We grew single crystals of USb and UTe with high purity using the Bridgman technique, and measured transport properties and specific heat. ((orig.))

  16. Crystallization kinetics of GeTe phase-change thin films grown by pulsed laser deposition

    Science.gov (United States)

    Sun, Xinxing; Thelander, Erik; Gerlach, Jürgen W.; Decker, Ulrich; Rauschenbach, Bernd

    2015-07-01

    Pulsed laser deposition was employed to the growth of GeTe thin films on Silicon substrates. X-ray diffraction measurements reveal that the critical crystallization temperature lies between 220 and 240 °C. Differential scanning calorimetry was used to investigate the crystallization kinetics of the as-deposited films, determining the activation energy to be 3.14 eV. Optical reflectivity and in situ resistance measurements exhibited a high reflectivity contrast of ~21% and 3-4 orders of magnitude drop in resistivity of the films upon crystallization. The results show that pulsed laser deposited GeTe films can be a promising candidate for phase-change applications.

  17. Crystallization kinetics of GeTe phase-change thin films grown by pulsed laser deposition

    International Nuclear Information System (INIS)

    Sun, Xinxing; Thelander, Erik; Gerlach, Jürgen W; Decker, Ulrich; Rauschenbach, Bernd

    2015-01-01

    Pulsed laser deposition was employed to the growth of GeTe thin films on Silicon substrates. X-ray diffraction measurements reveal that the critical crystallization temperature lies between 220 and 240 °C. Differential scanning calorimetry was used to investigate the crystallization kinetics of the as-deposited films, determining the activation energy to be 3.14 eV. Optical reflectivity and in situ resistance measurements exhibited a high reflectivity contrast of ∼21% and 3–4 orders of magnitude drop in resistivity of the films upon crystallization. The results show that pulsed laser deposited GeTe films can be a promising candidate for phase-change applications. (paper)

  18. Ute Unit: Study Guide and Follow Up Activities.

    Science.gov (United States)

    North Conejos School District, Capulin, CO.

    The study guide and follow-up activities were designed primarily to give students a feeling of Ute life in the San Luis Valley in Colorado. The unit begins with six Southern Ute stories about the wolf and coyote, the race between the skunk and the coyote, the frog and the eagle, why the frog croaks, the bear (Que Ye Qat), and the two Indian…

  19. In-situ CdS/CdTe Heterojuntions Deposited by Pulsed Laser Deposition

    KAUST Repository

    Avila-Avendano, Jesus

    2016-04-09

    In this paper pulsed laser deposition (PLD) methods are used to study p-n CdTe/CdS heterojunctions fabricated in-situ. In-situ film deposition allows higher quality p-n interfaces by minimizing spurious contamination from the atmosphere. Morphologic and structural analyses were carried for CdTe films deposited on various substrates and different deposition conditions. The electrical characteristics and performance of the resulting p-n heterojunctions were studied as function of substrate and post-deposition anneal temperature. In-situ growth results on diodes with a rectification factor of ~ 105, an ideality factor < 2, and a reverse saturation current ~ 10-8 A. The carrier concentration in the CdTe film was in the range of ~ 1015 cm-3, as measured by C-V methods. The possible impact of sulfur diffusion from the CdS into the CdTe film is also investigated using High Resolution Rutherford Back-Scattering.

  20. In-situ CdS/CdTe Heterojuntions Deposited by Pulsed Laser Deposition

    KAUST Repository

    Avila-Avendano, Jesus; Mejia, Israel; Alshareef, Husam N.; Guo, Zaibing; Young, Chadwin; Quevedo-Lopez, Manuel

    2016-01-01

    In this paper pulsed laser deposition (PLD) methods are used to study p-n CdTe/CdS heterojunctions fabricated in-situ. In-situ film deposition allows higher quality p-n interfaces by minimizing spurious contamination from the atmosphere. Morphologic and structural analyses were carried for CdTe films deposited on various substrates and different deposition conditions. The electrical characteristics and performance of the resulting p-n heterojunctions were studied as function of substrate and post-deposition anneal temperature. In-situ growth results on diodes with a rectification factor of ~ 105, an ideality factor < 2, and a reverse saturation current ~ 10-8 A. The carrier concentration in the CdTe film was in the range of ~ 1015 cm-3, as measured by C-V methods. The possible impact of sulfur diffusion from the CdS into the CdTe film is also investigated using High Resolution Rutherford Back-Scattering.

  1. Efficient optical trapping of CdTe quantum dots by femtosecond laser pulses

    KAUST Repository

    Chiang, Weiyi

    2014-12-11

    The development in optical trapping and manipulation has been showing rapid progress, most of it is in the small particle sizes in nanometer scales, substituting the conventional continuous-wave lasers with high-repetition-rate ultrashort laser pulse train and nonlinear optical effects. Here, we evaluate two-photon absorption in optical trapping of 2.7 nm-sized CdTe quantum dots (QDs) with high-repetition-rate femtosecond pulse train by probing laser intensity dependence of both Rayleigh scattering image and the two-photon-induced luminescence spectrum of the optically trapped QDs. The Rayleigh scattering imaging indicates that the two-photon absorption (TPA) process enhances trapping ability of the QDs. Similarly, a nonlinear increase of the two-photon-induced luminescence with the incident laser intensity fairly indicates the existence of the TPA process.

  2. Rapid pulse annealing of CdZnTe detectors for reducing electronic noise

    Science.gov (United States)

    Voss, Lars; Conway, Adam; Nelson, Art; Nikolic, Rebecca J.; Payne, Stephen A.; Swanberg, Jr., Erik Lars

    2018-05-01

    A combination of doping, rapid pulsed optical and/or thermal annealing, and unique detector structure reduces or eliminates sources of electronic noise in a CdZnTe (CZT) detector. According to several embodiments, methods of forming a detector exhibiting minimal electronic noise include: pulse-annealing at least one surface of a detector comprising CZT for one or more pulses, each pulse having a duration of .about.0.1 seconds or less. The at least one surface may optionally be ion-implanted. In another embodiment, a CZT detector includes a detector surface with two or more electrodes operating at different electric potentials and coupled to the detector surface; and one or more ion-implanted CZT surfaces on or in the detector surface, each of the one or more ion-implanted CZT surfaces being independently connected to one of the two or more electrodes and the surface of the detector. At least two of the ion-implanted surfaces are in electrical contact.

  3. Synthesis of ZnTe nanowires onto TiO2 nanotubular arrays by pulse-reverse electrodeposition

    International Nuclear Information System (INIS)

    Gandhi, T.; Raja, K.S.; Misra, M.

    2009-01-01

    Growth of ZnTe nanowires using a pulse-reverse electrodeposition technique from a non-aqueous solution is reported. ZnTe nanowires were grown on to an ordered nanotubular TiO 2 template in a propylene carbonate solution at 130 o C inside a controlled atmosphere glove box. The pulse-reverse electro deposition process consisted of a cathodic pulse at - 0.62 V and an anodic pulse at 0.75 V Vs Zn 2+ /Zn. Stoichiometry growth of crystalline ZnTe nanowires was observed in the as-deposited condition. The anodic pulse cycle of the pulse-reverse electrodeposition process presumably introduced zinc vacancies as deep level acceptors at an energy level of E v + 0.47 eV. The resultant ZnTe nanowires showed p-type semiconductivity with a resistivity of 7.8 x 10 4 Ω cm and a charge carrier density of 1.67 x 10 14 cm -3 . Annihilation of the defects occurred upon thermal annealing that resulted in marginal decrease in the defect density.

  4. Photoluminescence of CdTe nanocrystals grown by pulsed laser ablation on a template of Si nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Guillen-Cervantes, A.; Silva-Lopez, H.; Becerril-Silva, M.; Arias-Ceron, J.S.; Campos-Gonzalez, E.; Zelaya-Angel, O. [CINVESTAV-IPN, Physics Department, Apdo. Postal 14-740, Mexico (Mexico); Medina-Torres, A.C. [Escuela Superior de Fisica y Matematicas del IPN, Mexico (Mexico)

    2014-11-12

    CdTe nanocrystals were grown on eroded Si (111) substrates at room temperature by pulsed laser ablation. Before growth, Si substrates were subjected to different erosion time in order to investigate the effect on the CdTe samples. The erosion process consists of exposition to a pulsed high-voltage electric arc. The surface consequence of the erosion process consists of Si nanoparticles which acted as a template for the growth of CdTe nanocrystals. CdTe samples were studied by X-ray diffraction (XRD), room temperature photoluminescence (RT PL) and high-resolution transmission electron microscopy (HRTEM). CdTe nanocrystals grew in the stable cubic phase, according to XRD spectra. A strong visible emission was detected in photoluminescence (PL) experiments. The PL signal was centered at 540 nm (∝2.34 eV). With the effective mass approximation, the size of the CdTe crystals was estimated around 3.5 nm. HRTEM images corroborated the physical characteristics of CdTe nanocrystals. These results could be useful for the development of CdTe optoelectronic devices. (orig.)

  5. Investigation of ZnTe thin films grown by Pulsed Laser Deposition method

    International Nuclear Information System (INIS)

    Kotlyarchuk, B.; Savchuk, V.

    2007-01-01

    This paper is devoted to optimization of the Pulsed Laser Deposition (PLD) growth condition of ZnTe films on various substrates and subsequent investigation of relevant parameters of growth process, structural, optical and electrical properties of grown films. Studies of the effect of growth parameters on the structural quality and properties of grown films were carried out. X-ray diffraction measurements showed that the ZnTe films, which have been deposited at optimal substrate temperatures, were characterized by a (111) preferred orientation with large average grain size. The optical transmission and reflectance in the energy range 1.5-5.5 eV for films grown at various substrate temperatures were measured. We calculated the variation in the absorption coefficient with the photon energy from the transmittance spectrum for samples grown at various substrate temperatures. Obtained data were analyzed and the value of the absorption coefficient, for allowed direct transitions, has been determined as a function of photon energy. We found that the undoped ZnTe films, which were grown by the PLD method, are typically p-type and possess resistivity in the range of 10 3 Ωcm at room temperature. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Pulse shaping system research of CdZnTe radiation detector for high energy x-ray diagnostic

    Science.gov (United States)

    Li, Miao; Zhao, Mingkun; Ding, Keyu; Zhou, Shousen; Zhou, Benjie

    2018-02-01

    As one of the typical wide band-gap semiconductor materials, the CdZnTe material has high detection efficiency and excellent energy resolution for the hard X-ray and the Gamma ray. The generated signal of the CdZnTe detector needs to be transformed to the pseudo-Gaussian pulse with a small impulse-width to remove noise and improve the energy resolution by the following nuclear spectrometry data acquisition system. In this paper, the multi-stage pseudo-Gaussian shaping-filter has been investigated based on the nuclear electronic principle. The optimized circuit parameters were also obtained based on the analysis of the characteristics of the pseudo-Gaussian shaping-filter in our following simulations. Based on the simulation results, the falling-time of the output pulse was decreased and faster response time can be obtained with decreasing shaping-time τs-k. And the undershoot was also removed when the ratio of input resistors was set to 1 to 2.5. Moreover, a two stage sallen-key Gaussian shaping-filter was designed and fabricated by using a low-noise voltage feedback operation amplifier LMH6628. A detection experiment platform had been built by using the precise pulse generator CAKE831 as the imitated radiation pulse which was equivalent signal of the semiconductor CdZnTe detector. Experiment results show that the output pulse of the two stage pseudo-Gaussian shaping filter has minimum 200ns pulse width (FWHM), and the output pulse of each stage was well consistent with the simulation results. Based on the performance in our experiment, this multi-stage pseudo-Gaussian shaping-filter can reduce the event-lost caused by pile-up in the CdZnTe semiconductor detector and improve the energy resolution effectively.

  7. SU-F-J-112: Clinical Feasibility Test of An RF Pulse-Based MRI Method for the Quantitative Fat-Water Segmentation

    Energy Technology Data Exchange (ETDEWEB)

    Yee, S; Wloch, J; Pirkola, M [William Beaumont Hospital, Royal Oak, MI (United States)

    2016-06-15

    Purpose: Quantitative fat-water segmentation is important not only because of the clinical utility of fat-suppressed MRI images in better detecting lesions of clinical significance (in the midst of bright fat signal) but also because of the possible physical need, in which CT-like images based on the materials’ photon attenuation properties may have to be generated from MR images; particularly, as in the case of MR-only radiation oncology environment to obtain radiation dose calculation or as in the case of hybrid PET/MR modality to obtain attenuation correction map for the quantitative PET reconstruction. The majority of such fat-water quantitative segmentations have been performed by utilizing the Dixon’s method and its variations, which have to enforce the proper settings (often predefined) of echo time (TE) in the pulse sequences. Therefore, such methods have been unable to be directly combined with those ultrashort TE (UTE) sequences that, taking the advantage of very low TE values (∼ 10’s microsecond), might be beneficial to directly detect bones. Recently, an RF pulse-based method (http://dx.doi.org/10.1016/j.mri.2015.11.006), termed as PROD pulse method, was introduced as a method of quantitative fat-water segmentation that does not have to depend on predefined TE settings. Here, the clinical feasibility of this method is verified in brain tumor patients by combining the PROD pulse with several sequences. Methods: In a clinical 3T MRI, the PROD pulse was combined with turbo spin echo (e.g. TR=1500, TE=16 or 60, ETL=15) or turbo field echo (e.g. TR=5.6, TE=2.8, ETL=12) sequences without specifying TE values. Results: The fat-water segmentation was possible without having to set specific TE values. Conclusion: The PROD pulse method is clinically feasible. Although not yet combined with UTE sequences in our laboratory, the method is potentially compatible with UTE sequences, and thus, might be useful to directly segment fat, water, bone and air.

  8. Ablation of CdTe with 100 μs Nd:YAG laser pulses: dependence on target preparation method

    International Nuclear Information System (INIS)

    Rzeszutek, J.; Savchuk, V.; Oszwaldowski, M.

    2008-01-01

    The results of experimental studies of the ablation of CdTe with a pulsed Nd:YAG laser (wavelength 1064 nm) performed with 100 μs pulses and repetition time of 35 Hz are presented for the pulse energy range from 0.13 to 0.25 J. The main goal is to elucidate the dependence of the ablation process on the target preparation method. The investigation of the vapour stream intensity and chemical composition and their evolution with time are performed with a quadrupole mass spectrometer synchronized with the laser pulses. These studies are performed for three kinds of targets: a target made of CdTe bulk crystal (BC target), a target made of CdTe fine powder pressed under the pressure of 700 atm (PP target), and a target made of loose CdTe powder (N-PP target). The applicability of these targets for obtaining high quality CdTe thin films is determined. The best chemical composition of the vapour stream can be obtained with the BC target. A major drawback of this target is the energetic threshold for ablation with Nd:YAG laser and resulting delay in the ablation process above the threshold. The advantage of powder targets over BC target is the lack of any ablation threshold or delay. Weaker angular dependence of the particle emission (associated with the surface roughness), if confirmed in further experiments, can be the most important advantage of PP and N-PP targets. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Evolution of local structure in Ag2O-TeO2 glasses with addition of Ag2O analyzed by pulsed neutron diffraction and Raman spectroscopy

    International Nuclear Information System (INIS)

    Iwadate, Yasuhiko; Suzuki, Mineta; Hattori, Takeo; Fukushima, Kazuko; Nishiyama, Shin; Misawa, Masakatsu; Fukunaga, Toshiharu; Itoh, Keiji

    2005-01-01

    The local structure of Ag 2 O-TeO 2 glasses was studied by time-of-flight pulsed neutron diffraction (TOF-PND) and Raman spectroscopy. The results of Raman spectroscopy indicated that TeO 4 trigonal bipyramidal units (tbp) were converted to TeO 3 trigonal pyramidal units (tp) by addition of Ag 2 O to TeO 2 . Furthermore in PND, the structural parameters for each atomic pair were optimized in the Q-space, and the distances of the near neighbor Te-O correlations forming tbp units and tp units in the network were estimated with some accuracy

  10. Rewritable phase-change optical recording in Ge2Sb2Te5 films induced by picosecond laser pulses

    International Nuclear Information System (INIS)

    Siegel, J.; Schropp, A.; Solis, J.; Afonso, C.N.; Wuttig, M.

    2004-01-01

    The phase transformation dynamics induced in Ge 2 Sb 2 Te 5 films by picosecond laser pulses were studied using real-time reflectivity measurements with subnanosecond resolution. Evidence was found that the thermal diffusivity of the substrate plays a crucial role in determining the ability of the films to crystallize and amorphize. A film/substrate configuration with optimized heat flow conditions for ultrafast phase cycling with picosecond laser pulses was designed and produced. In this system, we achieved reversible phase transformations with large optical contrast (>20%) using single laser pulses with a duration of 30 ps within well-defined fluence windows. The amorphization (writing) process is completed within less than 1 ns, whereas crystallization (erasing) needs approximately 13 ns to be completed

  11. Low temperature epitaxy of Ge-Sb-Te films on BaF{sub 2} (111) by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Thelander, E., E-mail: erik.thelander@iom-leipzig.de; Gerlach, J. W.; Ross, U.; Lotnyk, A.; Rauschenbach, B. [Leibniz-Institut für Oberflächenmodifizierung e.V., Leipzig 04318 (Germany)

    2014-12-01

    Pulsed laser deposition was employed to deposit epitaxial Ge{sub 2}Sb{sub 2}Te{sub 5}-layers on the (111) plane of BaF{sub 2} single crystal substrates. X-ray diffraction measurements show a process temperature window for epitaxial growth between 85 °C and 295 °C. No crystalline growth is observed for lower temperatures, whereas higher temperatures lead to strong desorption of the film constituents. The films are of hexagonal structure with lattice parameters consistent with existing models. X-ray pole figure measurements reveal that the films grow with one single out-of-plane crystal orientation, but rotational twin domains are present. The out-of-plane epitaxial relationship is determined to be Ge{sub 2}Sb{sub 2}Te{sub 5}(0001) || BaF{sub 2}(111), whereas the in-plane relationship is characterized by two directions, i.e., Ge{sub 2}Sb{sub 2}Te{sub 5} [-12-10] || BaF{sub 2}[1-10] and Ge{sub 2}Sb{sub 2}Te{sub 5}[1-210] || BaF{sub 2}[1-10]. Aberration-corrected high-resolution scanning transmission electron microscopy was used to resolve the local atomic structure and confirm the hexagonal structure of the films.

  12. Characteristics of Ge-Sb-Te films prepared by cyclic pulsed plasma-enhanced chemical vapor deposition.

    Science.gov (United States)

    Suk, Kyung-Suk; Jung, Ha-Na; Woo, Hee-Gweon; Park, Don-Hee; Kim, Do-Heyoung

    2010-05-01

    Ge-Sb-Te (GST) thin films were deposited on TiN, SiO2, and Si substrates by cyclic-pulsed plasma-enhanced chemical vapor deposition (PECVD) using Ge{N(CH3)(C2H5)}, Sb(C3H7)3, Te(C3H7)3 as precursors in a vertical flow reactor. Plasma activated H2 was used as the reducing agent. The growth behavior was strongly dependent on the type of substrate. GST grew as a continuous film on TiN regardless of the substrate temperature. However, GST formed only small crystalline aggregates on Si and SiO2 substrates, not a continuous film, at substrate temperatures > or = 200 degrees C. The effects of the deposition temperature on the surface morphology, roughness, resistivity, crystallinity, and composition of the GST films were examined.

  13. Circles, Trees, and Bears: Symbols of Power of the Weenuche Ute

    Science.gov (United States)

    McPherson, Robert S.

    2012-01-01

    The Ute community of White Mesa, comprised of approximately 315 people, sits in the corner of southeastern Utah, eleven miles outside of Blanding. The residents, primarily of Weenuche Ute and Paiute ancestry, enjoy a cultural heritage that embraces elements from plains, mountain, and desert/Great Basin Indian culture. Among their religious…

  14. Functional imaging of murine hearts using accelerated self-gated UTE cine MRI

    NARCIS (Netherlands)

    Motaal, Abdallah G.; Noorman, Nils; de Graaf, Wolter L.; Hoerr, Verena; Florack, Luc M. J.; Nicolay, Klaas; Strijkers, Gustav J.

    2015-01-01

    We introduce a fast protocol for ultra-short echo time (UTE) Cine magnetic resonance imaging (MRI) of the beating murine heart. The sequence involves a self-gated UTE with golden-angle radial acquisition and compressed sensing reconstruction. The self-gated acquisition is performed asynchronously

  15. UTE-T2* mapping detects sub-clinical meniscus injury after anterior cruciate ligament tear

    Science.gov (United States)

    Williams, A.; Qian, Y.; Golla, S.; Chu, C.R.

    2018-01-01

    SUMMARY Objective Meniscus tear is a known risk factor for osteoarthritis (OA). Quantitative assessment of meniscus degeneration, prior to surface break-down, is important to identification of early disease potentially amenable to therapeutic interventions. This work examines the diagnostic potential of ultrashort echo time-enhanced T2* (UTE-T2*) mapping to detect human meniscus degeneration in vitro and in vivo in subjects at risk of developing OA. Design UTE-T2* maps of 16 human cadaver menisci were compared to histological evaluations of meniscal structural integrity and clinical magnetic resonance imaging (MRI) assessment by a musculoskeletal radiologist. In vivo UTE-T2* maps were compared in 10 asymptomatic subjects and 25 ACL-injured patients with and without concomitant meniscal tear. Results In vitro, UTE-T2* values tended to be lower in histologically and clinically normal meniscus tissue and higher in torn or degenerate tissue. UTE-T2* map heterogeneity reflected collagen disorganization. In vivo, asymptomatic meniscus UTE-T2* values were repeatable within 9% (root-mean-square average coefficient of variation). Posteromedial meniscus UTE-T2* values in ACL-injured subjects with clinically diagnosed medial meniscus tear (n = 10) were 87% higher than asymptomatics (n = 10, P meniscus degeneration. Further study is needed to determine whether elevated subsurface meniscus UTE-T2* values predict progression of meniscal degeneration and development of OA. PMID:22306000

  16. Refractive index modulation of Sb70Te30 phase-change thin films by multiple femtosecond laser pulses

    International Nuclear Information System (INIS)

    Lei, Kai; Wang, Yang; Jiang, Minghui; Wu, Yiqun

    2016-01-01

    In this study, the controllable effective refractive index modulation of Sb 70 Te 30 phase-change thin films between amorphous and crystalline states was achieved experimentally by multiple femtosecond laser pulses. The modulation mechanism was analyzed comprehensively by a spectral ellipsometer measurement, surface morphology observation, and two-temperature model calculations. We numerically demonstrate the application of the optically modulated refractive index of the phase-change thin films in a precisely adjustable color display. These results may provide further insights into ultrafast phase-transition mechanics and are useful in the design of programmable photonic and opto-electrical devices based on phase-change memory materials.

  17. 3D Ultrashort TE MRI for Evaluation of Cartilaginous Endplate of Cervical Disk In Vivo: Feasibility and Correlation With Disk Degeneration in T2-Weighted Spin-Echo Sequence.

    Science.gov (United States)

    Kim, Yeo Ju; Cha, Jang Gyu; Shin, Yoon Sang; Chaudhari, Akshay S; Suh, Young Ju; Hwan Yoon, Seung; Gold, Garry E

    2018-05-01

    The purpose of this study was to evaluate the feasibility of 3D ultrashort TE (UTE) MRI in depicting the cartilaginous endplate (CEP) and its abnormalities and to investigate the association between CEP abnormalities and disk degeneration on T2-weighted spin-echo (SE) MR images in cervical disks in vivo. Eight healthy volunteers and 70 patients were examined using 3-T MRI with the 3D UTE cones trajectory technique (TR/TE, 16.1/0.032, 6.6). In the volunteer study, quantitative and qualitative assessments of CEP depiction were conducted for the 3D UTE and T2-weighted SE imaging. In the patient study, CEP abnormalities were analyzed. Intersequence agreement between the images obtained with the first-echo 3D UTE sequence and the images created by subtracting the second-echo from the first-echo 3D UTE sequence (subtracted 3D UTE) and the intraobserver and interobserver agreements for 3D UTE overall were also tested. The CEP abnormalities on the 3D UTE images correlated with the Miyazaki grading of the T2-weighted SE images. In the volunteer study, the CEP was well visualized on 3D UTE images but not on T2-weighted SE images (p evaluation of CEP abnormalities, intersequence agreements were substantial to almost perfect, intraobserver agreements were substantial to almost perfect, and interobserver agreements were moderate to substantial (p T2-weighted SE MRI.

  18. Optimization of electrodeposited p-doped Sb{sub 2}Te{sub 3} thermoelectric films by millisecond potentiostatic pulses

    Energy Technology Data Exchange (ETDEWEB)

    Schumacher, Christian; Akinsinde, Lewis; Zastrow, Sebastian; Heiderich, Sonja; Toellner, William; Nielsch, Kornelius; Bachmann, Julien [Institute of Applied Physics, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg (Germany); Reinsberg, Klaus G.; Broekaert, Jose A.C. [Institute of Applied and Inorganic Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany); Rampelberg, Geert; Detavernier, Christophe [Department of Solid State Sciences, University of Ghent, Krijgslaan 281/S1, 9000 Ghent (Belgium)

    2012-03-15

    A systematic optimization of p-type Sb{sub 2}Te{sub 3} thermoelectric films made by potentiostatic electrodeposition on Au and stainless steel substrates is presented. The influence of the preparative parameters of deposition voltage, concentration, and the deposition method are investigated in a nitric acid solution. As a postdeposition step, the influence of annealing the films is investigated. The use of a potential-controlled millisecond-pulsed deposition method could improve both the morphology and the composition of the films. The samples are characterized in terms of composition, crystallinity, Seebeck coefficient, and electrical resistivity. Pulsed-deposited films exhibit Seebeck coefficients of up to 160 {mu}V K{sup -1} and an electrical conductivity of 280 S cm{sup -1} at room temperature, resulting in power factors of about 700 {mu}W m{sup -1} K{sup -2}. After annealing, power factors of maximum 852 {mu}W m{sup -1} K{sup -2} are achieved. Although the annealing of DC-deposited films significantly increased the power factor, they do not reach the values of the pulsed-deposited films in the preannealing state. Structural analysis is performed with X-ray diffraction and shows the crystalline structure of Sb{sub 2}Te{sub 3} films. The performance is tuned by annealing of deposited films up to 300 C under He atmosphere while performing in-situ X-ray diffraction and resistivity measurements. The chemical analysis of the films is performed by inductively coupled plasma optical emission spectroscopy (ICP-OES) as well as scanning electron microscope energy dispersive X-ray analysis (SEM-EDX). (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Effect of In Situ Thermal Annealing on Structural, Optical, and Electrical Properties of CdS/CdTe Thin Film Solar Cells Fabricated by Pulsed Laser Deposition

    Directory of Open Access Journals (Sweden)

    Alaa Ayad Al-mebir

    2016-01-01

    Full Text Available An in situ thermal annealing process (iTAP has been introduced before the common ex situ cadmium chloride (CdCl2 annealing to improve crystal quality and morphology of the CdTe thin films after pulsed laser deposition of CdS/CdTe heterostructures. A strong correlation between the two annealing processes was observed, leading to a profound effect on the performance of CdS/CdTe thin film solar cells. Atomic force microscopy and Raman spectroscopy show that the iTAP in the optimal processing window produces considerable CdTe grain growth and improves the CdTe crystallinity, which results in significantly improved optoelectronic properties and quantum efficiency of the CdS/CdTe solar cells. A power conversion efficiency of up to 7.0% has been obtained on thin film CdS/CdTe solar cells of absorber thickness as small as 0.75 μm processed with the optimal iTAP at 450°C for 10–20 min. This result illustrates the importance of controlling microstructures of CdTe thin films and iTAP provides a viable approach to achieve such a control.

  20. Preparation and characterization of pulsed laser deposited CdTe thin films at higher FTO substrate temperature and in Ar + O{sub 2} atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Chao; Ming, Zhenxun [College of Materials Science and Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Li, Bing, E-mail: libing70@126.com [College of Materials Science and Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Feng, Lianghuan [College of Materials Science and Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Wu, Judy [Department of Physics and Astronomy, Kansas University, Lawrence 66045 (United States)

    2013-06-20

    Highlights: • CdTe films were deposited by PLD at high substrate temperatures (400 °C, 550 °C). • CdTe films were achieved under the atmosphere (1.2 Torr) of Ar mixed with O{sub 2}. • Deposited CdTe films were cubic phase and had strong (1 0 0) preferred orientation. • Scanning electron microscope (SEM) showed an average grain size of 0.3–0.6 μm. • The ultra-thin film (CdS/PLD-CdTe) solar cell with efficiency of 6.68% was made. -- Abstract: Pulsed laser deposition (PLD) is one of the promising techniques for depositing cadmium telluride (CdTe) thin films. It has been reported that PLD CdTe thin films were almost deposited at the lower substrate temperatures (<300 °C) under vacuum conditions. However, the poor crystallinity of CdTe films prepared in this way renders them not conducive to the preparation of high-efficiency CdTe solar cells. To obtain high-efficiency solar cell devices, better crystallinity and more suitable grain size are needed, which requires the CdTe layer to be deposited by PLD at high substrate temperatures (>400 °C). In this paper, CdTe layers were deposited by PLD (KrF, λ = 248 nm, 10 Hz) at different higher substrate temperatures (T{sub s}). Excellent performance of CdTe films was achieved at higher substrate temperatures (400 °C, 550 °C) under an atmosphere of Ar mixed with O{sub 2} (1.2 Torr). X-ray diffraction analysis confirmed the formation of CdTe cubic phase with a strong (1 0 0) preferential orientation at all substrates temperatures on 60 mJ laser energy. The optical properties of CdTe were investigated, and the band gaps of CdTe films were 1.51 eV and 1.49 eV at substrate temperatures of 400 °C and 550 °C, respectively. Scanning electron microscopy (SEM) showed an average grain size of 0.3–0.6 μm. Thus, under these conditions of the atmosphere of Ar + O{sub 2} (15 Torr) and at the relatively high T{sub s} (500 °C), an thin-film (FTO/PLD-CdS (100 nm)/PLD-CdTe (∼1.5 μm)/HgTe: Cu/Ag) solar cell with an

  1. Sensitivity of quantitative UTE MRI to the biomechanical property of the temporomandibular joint disc

    International Nuclear Information System (INIS)

    Bae, Won C.; Biswas, Reni; Statum, Sheronda; Sah, Robert L.; Chung, Christine B.

    2014-01-01

    To quantify MR properties of discs from cadaveric human temporomandibular joints (TMJ) using quantitative conventional and ultrashort time-to-echo magnetic resonance imaging (UTE MRI) techniques and to corroborate regional variation in the MR properties with that of biomechanical indentation stiffness. This study was exempt from the institutional review board approval. Cadaveric (four donors, two females, 74 ± 10.7 years) TMJs were sliced (n = 14 slices total) sagittally and imaged using quantitative techniques of conventional spin echo T2 (SE T2), UTE T2*, and UTE T1rho. The discs were then subjected to biomechanical indentation testing, which is performed by compressing the tissue with the blunt end of a small solid cylinder. Regional variations in MR and indentation stiffness were correlated. TMJ of a healthy volunteer was also imaged to show in vivo feasibility. Using the ME SE T2 and the UTE T1rho techniques, a significant (each p 2 = 0.42) than SE T2 (R 2 = 0.19) or UTE T2* (R 2 = 0.02, p = 0.1) techniques. The UTE T1rho technique, applicable in vivo, facilitated quantitative evaluation of TMJ discs and showed a high sensitivity to biomechanical softening of the TMJ discs. With additional work, the technique may become a useful surrogate measure for loss of biomechanical integrity of TMJ discs reflecting degeneration. (orig.)

  2. Comparison of optical transients during the picosecond laser pulse-induced crystallization of GeSbTe and AgInSbTe phase-change thin films: Nucleation-driven versus growth-driven processes

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Guangfei [Key Laboratory of High Power Laser Materials, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Li, Simian [State Key Laboratory of Optoelectronic Materials and Technology, Department of Physics, Sun Yat-Sen University, Guangzhou 510275 (China); Huang, Huan [Key Laboratory of High Power Laser Materials, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Wang, Yang, E-mail: ywang@siom.ac.cn [Key Laboratory of High Power Laser Materials, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Lai, Tianshu, E-mail: stslts@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technology, Department of Physics, Sun Yat-Sen University, Guangzhou 510275 (China); Wu, Yiqun [Key Laboratory of High Power Laser Materials, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2013-09-01

    Direct comparison of the real-time in-situ crystallization behavior of as-deposited amorphous Ge{sub 2}Sb{sub 2}Te{sub 5} (GeSbTe) and Ag{sub 8}In{sub 14}Sb{sub 55}Te{sub 23} (AgInSbTe) phase-change thin films driven by picosecond laser pulses was performed by a time-resolved optical pump-probe technique with nanosecond resolution. Different optical transients showed various crystallization processes because of the dissimilar nucleation- and growth-dominated mechanisms of the two materials. The effects of laser pulse fluence, thermal conductive structure, and successive pulse irradiation on their crystallization dynamics were also discussed. A schematic was then established to describe the different crystallization processes beginning from the as-deposited amorphous state. The results may provide further insight into the phase-change mechanism under extra-non-equilibrium conditions and aid the development of ultrafast phase-change memory materials.

  3. Sensitivity of quantitative UTE MRI to the biomechanical property of the temporomandibular joint disc

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Won C.; Biswas, Reni; Statum, Sheronda [University of California-San Diego, Department of Radiology, San Diego, CA (United States); Sah, Robert L. [University of California-San Diego, Department of Bioengineering, La Jolla, CA (United States); Chung, Christine B. [University of California-San Diego, Department of Radiology, San Diego, CA (United States); VA San Diego Healthcare System, Department of Radiology, San Diego, CA (United States)

    2014-09-15

    To quantify MR properties of discs from cadaveric human temporomandibular joints (TMJ) using quantitative conventional and ultrashort time-to-echo magnetic resonance imaging (UTE MRI) techniques and to corroborate regional variation in the MR properties with that of biomechanical indentation stiffness. This study was exempt from the institutional review board approval. Cadaveric (four donors, two females, 74 ± 10.7 years) TMJs were sliced (n = 14 slices total) sagittally and imaged using quantitative techniques of conventional spin echo T2 (SE T2), UTE T2*, and UTE T1rho. The discs were then subjected to biomechanical indentation testing, which is performed by compressing the tissue with the blunt end of a small solid cylinder. Regional variations in MR and indentation stiffness were correlated. TMJ of a healthy volunteer was also imaged to show in vivo feasibility. Using the ME SE T2 and the UTE T1rho techniques, a significant (each p < 0.0001) inverse relation between MR and indentation stiffness properties was observed for the data in the lower range of stiffness. However, the strength of correlation was significantly higher (p < 0.05) for UTE T1rho (R{sup 2} = 0.42) than SE T2 (R{sup 2} = 0.19) or UTE T2* (R{sup 2} = 0.02, p = 0.1) techniques. The UTE T1rho technique, applicable in vivo, facilitated quantitative evaluation of TMJ discs and showed a high sensitivity to biomechanical softening of the TMJ discs. With additional work, the technique may become a useful surrogate measure for loss of biomechanical integrity of TMJ discs reflecting degeneration. (orig.)

  4. Characterization of paraffin based breast tissue equivalent phantom using a CdTe detector pulse height analysis.

    Science.gov (United States)

    Cubukcu, Solen; Yücel, Haluk

    2016-12-01

    In this study, paraffin was selected as a base material and mixed with different amounts of CaSO 4 ·2H 2 O and H 3 BO 3 compounds in order to mimic breast tissue. Slab phantoms were produced with suitable mixture ratios of the additives in the melted paraffin. Subsequently, these were characterized in terms of first half-value layer (HVL) in the mammographic X-ray range using a pulse-height spectroscopic analysis with a CdTe detector. Irradiations were performed in the energy range of 23-35 kV p under broad beam conditions from Mo/Mo and Mo/Rh target/filter combinations. X-ray spectra were acquired with a CdTe detector without and with phantom material interposition in increments of 1 cm thickness and then evaluated to obtain the transmission data. The net integral areas of the spectra for the slabs were used to plot the transmission curves and these curves were fitted to the Archer model function. The results obtained for the slabs were compared with those of standard mammographic phantoms such as CIRS BR series phantoms and polymethylmethacrylate plates (PMMA). From the evaluated transmission curves, the mass attenuation coefficients and HVLs of some mixtures are close to those of the commercially available standard mammography phantoms. Results indicated that when a suitable proportion of H 3 BO 3 and CaSO 4 ·2H 2 O is added to the paraffin, the resulting material may be a good candidate for a breast tissue equivalent phantom.

  5. Preparation and characterization of Ge2Sb2Te5 phase change films on elastic substrates by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Hongbing; Thelander, Erik; Benke, Julia; Rauschenbach, Bernd [Leibniz Institute of Surface Modification, 04318 Leipzig (Germany)

    2012-07-01

    Ge{sub 2}Sb{sub 2}Te{sub 5} (GST) thin films have attracted a great deal of interest as an active layer for data storage media due to its high switching rate and extremely good reversibility. Here we demonstrate the preparation of high-quality GST films on elastic polyimide substrates by pulsed laser deposition (PLD). The composition and chemical state of the films were investigated by energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS), respectively. The effect of annealing temperature on the crystalline nature of the films was also studied. As-deposited films were found to be amorphous. Crystalline phases with face-centered cubic and hexagonal structures appeared at 180 and 300 degrees, respectively. Importantly, no phase separation could be seen in the annealed films. Furthermore, reflectivity measurements were performed to characterize the as-deposited and annealed films, showing a high reflectivity contrast (up to 23%) between full crystalline and amorphous films. Our results indicate that PLD deposited GST film on polyimide substrate is a promising candidate for use in future flexible memory devices.

  6. Decree 284/12. It regulate the servitudes prescribed by decree law 10.383 referring of UTE conduction lines energy

    International Nuclear Information System (INIS)

    2012-01-01

    This decree is about the UTE transmission line which integrate the Uruguayan National Electricity System. This regulation are able to allow an increasing energy demand as well as a better public service, a main purpose of UTE.

  7. Photoelectric properties by interface effect of organic/inorganic(CuPc/PbTe) multilayer prepared by pulsed laser deposition and thermal evaporation

    CERN Document Server

    Lee, H Y; Choi, B C; Jeong, J H; Tabata, H; Kawai, T

    1999-01-01

    Highly crystallized CuPc/PbTe multilayer are prepared at substrate temperature from room temperature to 300 .deg. C by pulsed laser deposition and thermal evaporation method. From the measurement of AFM image, these all film exhibits composed of round grains and flat matrix. For observation the interface effect of multilayer, we measured the transverse current-voltage characteristics in the dark and under illumination. The photocarrier is generated in the CuPc layer and the electron-hole pairs are separated by the steep incline of the potential near the CuPc/PbTe interface. The CuPc/PbTe multilayers in the in-plane current-voltage curve exhibit larger photoconduction effect than that of CuPc single layer.

  8. Quantitative 3D ultrashort time-to-echo (UTE) MRI and micro-CT (μCT) evaluation of the temporomandibular joint (TMJ) condylar morphology

    Energy Technology Data Exchange (ETDEWEB)

    Geiger, Daniel [Sapienza University of Rome, Department of Radiological, Oncological and Pathological Sciences, Rome (Italy); Bae, Won C.; Statum, Sheronda; Du, Jiang; Chung, Christine B. [University of California-San Diego, Department of Radiology, San Diego, CA (United States)

    2014-01-15

    Temporomandibular dysfunction involves osteoarthritis of the TMJ, including degeneration and morphologic changes of the mandibular condyle. The purpose of this study was to determine the accuracy of novel 3D-UTE MRI versus micro-CT (μCT) for quantitative evaluation of mandibular condyle morphology. Nine TMJ condyle specimens were harvested from cadavers (2 M, 3 F; age 85 ± 10 years, mean ± SD). 3D-UTE MRI (TR = 50 ms, TE = 0.05 ms, 104-μm isotropic-voxel) was performed using a 3-T MR scanner and μCT (18-μm isotropic-voxel) was also performed. MR datasets were spatially registered with a μCT dataset. Two observers segmented bony contours of the condyles. Fibrocartilage was segmented on the MR dataset. Using a custom program, bone and fibrocartilage surface coordinates, Gaussian curvature, volume of segmented regions, and fibrocartilage thickness were determined for quantitative evaluation of joint morphology. Agreement between techniques (MRI vs. μCT) and observers (MRI vs. MRI) for Gaussian curvature, mean curvature, and segmented volume of the bone were determined using intraclass correlation coefficient (ICC) analysis. Between MRI and μCT, the average deviation of surface coordinates was 0.19 ± 0.15 mm, slightly higher than the spatial resolution of MRI. Average deviation of the Gaussian curvature and volume of segmented regions, from MRI to μCT, was 5.7 ± 6.5 % and 6.6 ± 6.2 %, respectively. ICC coefficients (MRI vs. μCT) for Gaussian curvature, mean curvature, and segmented volumes were 0.892, 0.893, and 0.972, respectively. Between observers (MRI vs. MRI), the ICC coefficients were 0.998, 0.999, and 0.997, respectively. Fibrocartilage thickness was 0.55 ± 0.11 mm, as previously described in the literature for grossly normal TMJ samples. 3D-UTE MR quantitative evaluation of TMJ condyle morphology ex-vivo, including surface, curvature, and segmented volume, shows high correlation against μCT and between observers. In addition, UTE MRI allows

  9. PET/MR: improvement of the UTE μ-maps using modified MLAA

    Energy Technology Data Exchange (ETDEWEB)

    Benoit, Didier [Rigshospitalet, University of Copenhagen (Denmark); Ladefoged, Claes [Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet Copenhagen (Denmark); Rezaei, Ahmadreza [University of Leuven (Belgium); Keller, Sune; Andersen, Flemming; Hojgaard, Liselotte [Rigshospitalet, University of Copenhagen (Denmark); Hansen, Adam Espe [Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet Copenhagen (Denmark); Holm, Soren [Rigshospitalet, University of Copenhagen (Denmark); Nuyts, Johan [University of Leuven (Belgium)

    2015-05-18

    For a quantitative analysis in positron emission tomography (PET) or single-photon emission computed tomography (SPECT), attenuation correction (AC) is mandatory. CTscans or transmission scans are common tools for determination of the attenuation μ-map, but in the case of a PET/MR hybrid system it is difficult to associate one of these scans. Many techniques have been developed in order to improve AC for PET/MR. Some methods are based on template- or atlas techniques, other methods apply a segmentation technique based on Dixon or UTE (Ultrashort Echo Time) MR to create the μ-map, followed by a standard OSEM reconstruction (OSEM/DIXON and OSEM/UTE). A different approach for AC has been developed by employing the emission sinogram data in the μ-map derivation. In this context, we modified the iterative MLAA (Maximum-Likelihood reconstruction of Attenuation and Activity) algorithm to improve the resulting emission image from the PET/MR system. We constrained the attenuation map update using the UTE μ-map and the T1-weighted (T1w) MR image in order to improve convergence towards a solution. Results show that the modified MLAA algorithm improved the estimated emission image compared to standard OSEM/UTE and OSEM/DIXON. In certain regions of the brain, in particular close to the skull and the air cavities, the modified MLAA algorithm generated less error than OSEM/UTE and OSEM/Dixon. The modified MLAA algorithm is able to compute an attenuation μ-map that is slightly more similar to the aligned CT μ-map than the UTE μ-map.

  10. MULTICOMPONENT SEISMIC ANALYSIS AND CALIBRATION TO IMPROVE RECOVERY FROM ALGAL MOUNDS: APPLICATION TO THE ROADRUNNER/TOWAOC AREA OF THE PARADOX BASIN, UTE MOUNTAIN UTE RESERVATION, COLORADO

    International Nuclear Information System (INIS)

    Paul La Pointe; Claudia Rebne; Steve Dobbs

    2004-01-01

    This report describes the results made in fulfillment of contract DE-FG26-02NT15451, ''Multicomponent Seismic Analysis and Calibration to Improve Recovery from Algal Mounds: Application to the Roadrunner/Towaoc Area of the Paradox Basin, Ute Mountain Ute Reservation, Colorado'', for the Second Biennial Report covering the time period May 1, 2003 through October 31, 2003. During this period, the project achieved two significant objectives: completion of the acquisition and processing design and specifications 3D9C seismic acquisition and the 3D VSP log; and completion of the permitting process involving State, Tribal and Federal authorities. Successful completion of these two major milestones pave the way for field acquisition as soon as weather permits in the Spring of 2004. This report primarily describes the design and specifications for the VSP and 3D9C surveys

  11. Utes for space heating and cooling in North Africa

    International Nuclear Information System (INIS)

    Nordell, B.; Grein, M. a.

    2006-01-01

    The North Africa climate is dry and warm with annual mean temperature from 15 degree centigrade to 25 degree centigrade, with a temperature difference of 20 degree centigrade between the coldest and warmest month. Heating is needed during the short winter and there is a large cooling demand during the long summer. Since the undisturbed ground temperature is equal to the annual mean air temperature, the ground is warmer than the air during the winter and colder than air during summer. This is what is required for the direct use of the ground for heating and cooling. In such systems, ground coupled heating and cooling systems, and also in storage systems, Underground Thermal Energy Storage (UTES), some kind of underground duct (PIPE) system is used to inject or extract heat from the ground. Thermal energy is then stored and recovered by heating and cooling of the ground, while the ducts are the heat exchangers with the system. The duct system could be placed horizontally or vertically (e.g. in boreholes) in the ground. In many cases heat pumps or cooling machines are included in the systems but in favourable cases, such as in the North African climate, the ground can be used directly for heating and cooling. then, only a circulation pump is used to pump water through the underground duct system with high efficiencies. Such systems can also be used for thermal energy storage, during shorter periods (diurnal) or even between the seasons. In September 2005 Sebha University and Luleu University of Technology started a Libyan Swedish collaboration to develop and implement these systems for the North African climate. Sweden has considerable experience in ground coupled systems, theoretically and practically, and there are presently more than 300.000 systems in operation in Sweden, mainly for heating. Most of these are small-scale heating systems for singe-family houses but during the last decade several hundred large-scale systems have been built for heating and cooling of

  12. Suspension kinematic analysis of UTeM’s FV Malaysia electric vehicle racing car

    NARCIS (Netherlands)

    Abdul Manaf, M.Z.; Latif, M.F.A.; Razak, M.S.A.; Hassan, M.Z.B.; Rosley, M.I.F.

    2016-01-01

    The purpose of this paper is to investigate the kinematic performance of students’ racing car, namely UTeM’s FV Malaysia Electric Vehicle. An elasto-kinematic analysis approach is used to predict the car’s performance during straight line drive and curvature drive. Two suspension design factors

  13. Electrical characterization of the temperature dependence in CdTe/CdS heterojunctions deposited in-situ by pulsed laser deposition

    Science.gov (United States)

    Avila-Avendano, Jesus; Quevedo-Lopez, Manuel; Young, Chadwin

    2018-02-01

    The I-V and C-V characteristics of CdTe/CdS heterojunctions deposited in-situ by Pulsed Laser Deposition (PLD) were evaluated. In-situ deposition enables the study of the CdTe/CdS interface by avoiding potential impurities at the surface and interface as a consequence of exposure to air. The I-V and C-V characteristics of the resulting junctions were obtained at different temperatures, ranging from room temperature to 150 °C, where the saturation current (from 10-8 to 10-4 A/cm2), ideality factor (between 1 and 2), series resistance (from 102 to 105 Ω), built-in potential (0.66-0.7 V), rectification factor (˜106), and carrier concentration (˜1016 cm-3) were obtained. The current-voltage temperature dependence study indicates that thermionic emission is the main transport mechanism at the CdTe/CdS interface. This study also demonstrated that the built-in potential (Vbi) calculated using a thermionic emission model is more accurate than that calculated using C-V extrapolation since C-V plots showed a Vbi shift as a function of frequency. Although CdTe/CdS is widely used for photovoltaic applications, the parameters evaluated in this work indicate that CdTe/CdS heterojunctions could be used as rectifying diodes and junction field effect transistors (JFETs). JFETs require a low PN diode saturation current, as demonstrated for the CdTe/CdS junction studied here.

  14. A novel segmentation approach for implementation of MRAC in head PET/MRI employing Short-TE MRI and 2-point Dixon method in a fuzzy C-means framework

    Energy Technology Data Exchange (ETDEWEB)

    Khateri, Parisa; Rad, Hamidreza Saligheh [Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Jafari, Amir Homayoun [Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Ay, Mohammad Reza, E-mail: mohammadreza_ay@tums.ac.ir [Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of)

    2014-01-11

    Quantitative PET image reconstruction requires an accurate map of attenuation coefficients of the tissue under investigation at 511 keV (μ-map), and in order to correct the emission data for attenuation. The use of MRI-based attenuation correction (MRAC) has recently received lots of attention in the scientific literature. One of the major difficulties facing MRAC has been observed in the areas where bone and air collide, e.g. ethmoidal sinuses in the head area. Bone is intrinsically not detectable by conventional MRI, making it difficult to distinguish air from bone. Therefore, development of more versatile MR sequences to label the bone structure, e.g. ultra-short echo-time (UTE) sequences, certainly plays a significant role in novel methodological developments. However, long acquisition time and complexity of UTE sequences limit its clinical applications. To overcome this problem, we developed a novel combination of Short-TE (ShTE) pulse sequence to detect bone signal with a 2-point Dixon technique for water–fat discrimination, along with a robust image segmentation method based on fuzzy clustering C-means (FCM) to segment the head area into four classes of air, bone, soft tissue and adipose tissue. The imaging protocol was set on a clinical 3 T Tim Trio and also 1.5 T Avanto (Siemens Medical Solution, Erlangen, Germany) employing a triple echo time pulse sequence in the head area. The acquisition parameters were as follows: TE1/TE2/TE3=0.98/4.925/6.155 ms, TR=8 ms, FA=25 on the 3 T system, and TE1/TE2/TE3=1.1/2.38/4.76 ms, TR=16 ms, FA=18 for the 1.5 T system. The second and third echo-times belonged to the Dixon decomposition to distinguish soft and adipose tissues. To quantify accuracy, sensitivity and specificity of the bone segmentation algorithm, resulting classes of MR-based segmented bone were compared with the manual segmented one by our expert neuro-radiologist. Results for both 3 T and 1.5 T systems show that bone segmentation applied in several

  15. A novel segmentation approach for implementation of MRAC in head PET/MRI employing Short-TE MRI and 2-point Dixon method in a fuzzy C-means framework

    Science.gov (United States)

    Khateri, Parisa; Rad, Hamidreza Saligheh; Jafari, Amir Homayoun; Ay, Mohammad Reza

    2014-01-01

    Quantitative PET image reconstruction requires an accurate map of attenuation coefficients of the tissue under investigation at 511 keV (μ-map), and in order to correct the emission data for attenuation. The use of MRI-based attenuation correction (MRAC) has recently received lots of attention in the scientific literature. One of the major difficulties facing MRAC has been observed in the areas where bone and air collide, e.g. ethmoidal sinuses in the head area. Bone is intrinsically not detectable by conventional MRI, making it difficult to distinguish air from bone. Therefore, development of more versatile MR sequences to label the bone structure, e.g. ultra-short echo-time (UTE) sequences, certainly plays a significant role in novel methodological developments. However, long acquisition time and complexity of UTE sequences limit its clinical applications. To overcome this problem, we developed a novel combination of Short-TE (ShTE) pulse sequence to detect bone signal with a 2-point Dixon technique for water-fat discrimination, along with a robust image segmentation method based on fuzzy clustering C-means (FCM) to segment the head area into four classes of air, bone, soft tissue and adipose tissue. The imaging protocol was set on a clinical 3 T Tim Trio and also 1.5 T Avanto (Siemens Medical Solution, Erlangen, Germany) employing a triple echo time pulse sequence in the head area. The acquisition parameters were as follows: TE1/TE2/TE3=0.98/4.925/6.155 ms, TR=8 ms, FA=25 on the 3 T system, and TE1/TE2/TE3=1.1/2.38/4.76 ms, TR=16 ms, FA=18 for the 1.5 T system. The second and third echo-times belonged to the Dixon decomposition to distinguish soft and adipose tissues. To quantify accuracy, sensitivity and specificity of the bone segmentation algorithm, resulting classes of MR-based segmented bone were compared with the manual segmented one by our expert neuro-radiologist. Results for both 3 T and 1.5 T systems show that bone segmentation applied in several

  16. Refractive index modulation of Sb{sub 70}Te{sub 30} phase-change thin films by multiple femtosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Kai; Wang, Yang, E-mail: ywang@siom.ac.cn; Jiang, Minghui; Wu, Yiqun [Key Laboratory of High Power Laser Materials, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2016-05-07

    In this study, the controllable effective refractive index modulation of Sb{sub 70}Te{sub 30} phase-change thin films between amorphous and crystalline states was achieved experimentally by multiple femtosecond laser pulses. The modulation mechanism was analyzed comprehensively by a spectral ellipsometer measurement, surface morphology observation, and two-temperature model calculations. We numerically demonstrate the application of the optically modulated refractive index of the phase-change thin films in a precisely adjustable color display. These results may provide further insights into ultrafast phase-transition mechanics and are useful in the design of programmable photonic and opto-electrical devices based on phase-change memory materials.

  17. The Ute Campaign of 1879: A Study in the Use of the Military Instrument

    Science.gov (United States)

    1993-06-04

    theater--General Philip St. George Cooke--and he was relieved following the Fetterman massacre in December of that year."s The capabilities of a modern...Abbott, Stephen J. Leonard, David McComb, Colorado: A History of the Centennial State (Boulder: University Press of Colorado, 1982), 26. 65 33. John H...Nankivell, "Fort Garland, Colorado,- The Colorado Magazine 16 (January 1939): 13. 34. P. David Smith, Ouray: Chief of the Utes (Salt Lake City

  18. High power pulse electron beam modification and ion implantation of Hg{sub 1-x}Cd{sub x}Te crystals

    Energy Technology Data Exchange (ETDEWEB)

    Vojtsekhovskij, A V; Remnev, G E [Tomsk Polytechnic Univ. (Russian Federation). Nuclear Physics Inst.; Opekunov, M S; Kokhanenko, A P; Korotaev, A G; Denisov, Yu A; Oucherenko, D A [Tomsk State Univ. (Russian Federation). Dept. of Radiophysics

    1997-12-31

    Hg{sub 1-x}Cd{sub x}Te (MCT) samples (x = 0.21 - 0.22) were irradiated by pulse electron beams at doses of 10{sup 13} to 10{sup 17} cm{sup -2}. The electron beams possessed the following parameters: 500 keV electron energy (30-40 A/cm{sup 2} electron current density, 60-80 ns current pulse); 200 keV electron energy (8- 10 A/cm{sup 2} electron current density, 100-200 ns current pulse). The electric conductivity and recombination of modified samples were investigated by the Hall effect and photoconductivity methods. For the 200 keV electron energy beam irradiation, the n-type surface regions were obtained under threshold mechanisms of donor defect generation. For the 500 keV electron energy beam irradiation, the maximum value of charge carrier lifetimes occur in the p- to n-type conductivity conversion range for the initial p-type crystals due to the conductivity compensation. MCT samples (x = 0.21 - 0.22) were implanted with Al ions at doses of 10{sup 12}-10{sup 16} cm{sup -2}. The ion beams possessed the following parameters: (1-10) A/cm{sup 2} ion current density, (100-200) ns current pulse; (150-450) keV Al ion (Al{sup +},Al{sup ++}, Al{sup +++}). The ion distribution and doping profiles were investigated by PIGE and Hall effect methods. Comparison between MCT samples after power pulse ion implantation and after standard ion implantation demonstrates differences in ion distribution, doping profiles and defect formation radiation mechanisms. (author). 3 figs., 8 refs.

  19. High-power and long-pulse operation of TE{sub 31,11} mode gyrotron

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, Ryosuke, E-mail: ikeda.ryosuke@jaea.go.jp; Kajiwara, Ken; Oda, Yasuhisa; Takahashi, Koji; Sakamoto, Keishi

    2015-10-15

    Highlights: • We are under development of TE{sub 31,11} mode gyrotron to aim ITER specification. • HE{sub 11} mode purity reached 96% of ITER specification. • Mode competition was suppressed in initial phase of oscillation by anode voltage control. • Maximum output power of 1.2 MW was achieved. • Steady state operation of 500 MJ was achieved. - Abstract: The ITER electron cyclotron system is designed to inject a 20 MW RF beam by using twenty-four 170 GHz/1 MW gyrotrons. JAEA is currently developing a gyrotron having a high-order mode (TE{sub 31,11}) to reduce the heat load in the cavity resonator and achieve an output power greater than 1 MW. The measured radiation profile at the front of the diamond window agreed with the results of the calculation. In order to suppress RF loss in the equatorial and upper port launchers, a high-quality HE{sub 11} mode is required at the exit of the matching optics unit (MOU). An HE{sub 11} mode purity of 96% was achieved by finely adjusting the two mirrors in the MOU. During the oscillation start-up phase, mode competition with counter-rotating TE{sub 29,12} mode was observed on the higher magnetic field side which caused arcing and pressure increase in the gyrotron. To avoid the counter-rotating TE{sub 29,12} mode from being excited, a start-up scenario that controls the voltage between the anode and cathode electrodes at the initial phase of operation was introduced, which was able to achieve a stable start-up of TE{sub 31,11} mode. A 1.2 MW output power having a total electric efficiency of 43% was obtained in high-power experiments. In steady-state operation, a 1000 s oscillation length and output power of 0.51 MW was achieved.

  20. Skull segmentation of UTE MR images by probabilistic neural network for attenuation correction in PET/MR

    Energy Technology Data Exchange (ETDEWEB)

    Santos Ribeiro, A. [Institute of Biophysics and Biomedical Engineering, Lisbon (Portugal); Forschungszentrum Juelich, INM4, Juelich (Germany); Rota Kops, E., E-mail: e.rota.kops@fz-juelich.de [Forschungszentrum Juelich, INM4, Juelich (Germany); Herzog, H. [Forschungszentrum Juelich, INM4, Juelich (Germany); Almeida, P. [Institute of Biophysics and Biomedical Engineering, Lisbon (Portugal)

    2013-02-21

    Aim: Due to space and technical limitations in PET/MR scanners one of the difficulties is the generation of an attenuation correction (AC) map to correct the PET image data. Different methods have been suggested that make use of the images acquired with an ultrashort echo time (UTE) sequence. However, in most of them precise thresholds need to be defined and these may depend on the sequence parameters. In this study an algorithm based on a probabilistic neural network (PNN) is presented requiring little user interaction. Material and methods: An MR UTE sequence delivering two images (UTE1 and UTE2) by using two different echo times (0.07 ms and 2.46 ms, respectively) was acquired. The input features for the PNN algorithm consist of two patches of MR intensities chosen in both the co-registered UTE1 and UTE2 images. At the end, the PNN generates an image classified into four different classes: brain+soft tissue, air, csf, and bone. CT and MR data were acquired in four subjects, whereby the CT data were used for comparison. For each patient co-classification of the different classified classes and the Dice coefficients (D) were calculated between the MR segmented image and the respective CT image. Results: An overall voxel classification accuracy (compared with CT) of 92% was obtained. Also, the resulting D with regard to the skull and calculated for the four subjects show a mean of 0.83 and a standard deviation of 0.07. Discussion: Our results show that a reliable bone segmentation of MRI images as well as the generation of a reliable attenuation map is possible. Conclusion: The developed algorithms possess several advantages over current methods using UTE sequence such as a quick and an easy optimization for different sequence parameters.

  1. Skull segmentation of UTE MR images by probabilistic neural network for attenuation correction in PET/MR

    International Nuclear Information System (INIS)

    Santos Ribeiro, A.; Rota Kops, E.; Herzog, H.; Almeida, P.

    2013-01-01

    Aim: Due to space and technical limitations in PET/MR scanners one of the difficulties is the generation of an attenuation correction (AC) map to correct the PET image data. Different methods have been suggested that make use of the images acquired with an ultrashort echo time (UTE) sequence. However, in most of them precise thresholds need to be defined and these may depend on the sequence parameters. In this study an algorithm based on a probabilistic neural network (PNN) is presented requiring little user interaction. Material and methods: An MR UTE sequence delivering two images (UTE1 and UTE2) by using two different echo times (0.07 ms and 2.46 ms, respectively) was acquired. The input features for the PNN algorithm consist of two patches of MR intensities chosen in both the co-registered UTE1 and UTE2 images. At the end, the PNN generates an image classified into four different classes: brain+soft tissue, air, csf, and bone. CT and MR data were acquired in four subjects, whereby the CT data were used for comparison. For each patient co-classification of the different classified classes and the Dice coefficients (D) were calculated between the MR segmented image and the respective CT image. Results: An overall voxel classification accuracy (compared with CT) of 92% was obtained. Also, the resulting D with regard to the skull and calculated for the four subjects show a mean of 0.83 and a standard deviation of 0.07. Discussion: Our results show that a reliable bone segmentation of MRI images as well as the generation of a reliable attenuation map is possible. Conclusion: The developed algorithms possess several advantages over current methods using UTE sequence such as a quick and an easy optimization for different sequence parameters

  2. MULTICOMPONENT SEISMIC ANALYSIS AND CALIBRATION TO IMPROVE RECOVERY FROM ALGAL MOUNDS: APPLICATION TO THE ROADRUNNER/TOWAOC AREA OF THE PARADOX BASIN, UTE MOUNTAIN UTE RESERVATION, COLORADO

    International Nuclear Information System (INIS)

    Paul La Pointe; Claudia Rebne; Steve Dobbs

    2003-01-01

    This report describes the results made in fulfillment of contract DE-FG26-02NT15451, ''Multicomponent Seismic Analysis and Calibration to Improve Recovery from Algal Mounds: Application to the Roadrunner/Towaoc Area of the Paradox Basin, Ute Mountain Ute Reservation, Colorado''. Optimizing development of highly heterogeneous reservoirs where porosity and permeability vary in unpredictable ways due to facies variations can be challenging. An important example of this is in the algal mounds of the Lower and Upper Ismay reservoirs of the Paradox Basin in Utah and Colorado. It is nearly impossible to develop a forward predictive model to delineate regions of better reservoir development, and so enhanced recovery processes must be selected and designed based upon data that can quantitatively or qualitatively distinguish regions of good or bad reservoir permeability and porosity between existing well control. Recent advances in seismic acquisition and processing offer new ways to see smaller features with more confidence, and to characterize the internal structure of reservoirs such as algal mounds. However, these methods have not been tested. This project will acquire cutting edge, three-dimensional, nine-component (3D9C) seismic data and utilize recently-developed processing algorithms, including the mapping of azimuthal velocity changes in amplitude variation with offset, to extract attributes that relate to variations in reservoir permeability and porosity. In order to apply advanced seismic methods a detailed reservoir study is needed to calibrate the seismic data to reservoir permeability, porosity and lithofacies. This will be done by developing a petrological and geological characterization of the mounds from well data; acquiring and processing the 3D9C data; and comparing the two using advanced pattern recognition tools such as neural nets. In addition, should the correlation prove successful, the resulting data will be evaluated from the perspective of

  3. Improved UTE-based attenuation correction for cranial PET-MR using dynamic magnetic field monitoring

    International Nuclear Information System (INIS)

    Aitken, A. P.; Giese, D.; Tsoumpas, C.; Schleyer, P.; Kozerke, S.; Prieto, C.; Schaeffter, T.

    2014-01-01

    Purpose: Ultrashort echo time (UTE) MRI has been proposed as a way to produce segmented attenuation maps for PET, as it provides contrast between bone, air, and soft tissue. However, UTE sequences require samples to be acquired during rapidly changing gradient fields, which makes the resulting images prone to eddy current artifacts. In this work it is demonstrated that this can lead to misclassification of tissues in segmented attenuation maps (AC maps) and that these effects can be corrected for by measuring the true k-space trajectories using a magnetic field camera. Methods: The k-space trajectories during a dual echo UTE sequence were measured using a dynamic magnetic field camera. UTE images were reconstructed using nominal trajectories and again using the measured trajectories. A numerical phantom was used to demonstrate the effect of reconstructing with incorrect trajectories. Images of an ovine leg phantom were reconstructed and segmented and the resulting attenuation maps were compared to a segmented map derived from a CT scan of the same phantom, using the Dice similarity measure. The feasibility of the proposed method was demonstrated inin vivo cranial imaging in five healthy volunteers. Simulated PET data were generated for one volunteer to show the impact of misclassifications on the PET reconstruction. Results: Images of the numerical phantom exhibited blurring and edge artifacts on the bone–tissue and air–tissue interfaces when nominal k-space trajectories were used, leading to misclassification of soft tissue as bone and misclassification of bone as air. Images of the tissue phantom and thein vivo cranial images exhibited the same artifacts. The artifacts were greatly reduced when the measured trajectories were used. For the tissue phantom, the Dice coefficient for bone in MR relative to CT was 0.616 using the nominal trajectories and 0.814 using the measured trajectories. The Dice coefficients for soft tissue were 0.933 and 0.934 for the

  4. PET/MR brain imaging: evaluation of clinical UTE-based attenuation correction

    International Nuclear Information System (INIS)

    Aasheim, Lars Birger; Karlberg, Anna; Goa, Paal Erik; Haaberg, Asta; Soerhaug, Sveinung; Fagerli, Unn-Merete; Eikenes, Live

    2015-01-01

    One of the greatest challenges in PET/MR imaging is that of accurate MR-based attenuation correction (AC) of the acquired PET data, which must be solved if the PET/MR modality is to reach its full potential. The aim of this study was to investigate the performance of Siemens' most recent version (VB20P) of MR-based AC of head PET data, by comparing it to CT-based AC. Methods: 18 F-FDG PET data from seven lymphoma and twelve lung cancer patients examined with a Biograph mMR PET/MR system were reconstructed with both CT-based and MR-based AC, avoiding sources of error arising when comparing PET data from different systems. The resulting images were compared quantitatively by measuring changes in mean SUV in ten different brain regions in both hemispheres, as well as the brainstem. In addition, the attenuation maps (μ maps) were compared regarding volume and localization of cranial bone. The UTE μ maps clearly overestimate the amount of bone in the neck, while slightly underestimating the amount of bone in the cranium, and the localization of bone in the cranial region also differ from the CT μ maps. In air/tissue interfaces in the sinuses and ears, the MRAC method struggles to correctly classify the different tissues. The misclassification of tissue is most likely caused by a combination of artefacts and the insufficiency of the UTE method to accurately separate bone. Quantitatively, this results in a combination of overestimation (0.5-3.6 %) and underestimation (2.7-5.2 %) of PET activity throughout the brain, depending on the proximity to the inaccurate regions. Our results indicate that the performance of the UTE method as implemented in VB20P is close to the theoretical maximum of such an MRAC method in the brain, while it does not perform satisfactorily in the neck or face/nasal area. Further improvement of the UTE MRAC or other available methods for more accurate segmentation of bone should be incorporated. (orig.)

  5. Variable flip angle 3D ultrashort echo time (UTE) T1 mapping of mouse lung: A repeatability assessment.

    Science.gov (United States)

    Alamidi, Daniel F; Smailagic, Amir; Bidar, Abdel W; Parker, Nicole S; Olsson, Marita; Hockings, Paul D; Lagerstrand, Kerstin M; Olsson, Lars E

    2018-03-08

    Lung T 1 is a potential translational biomarker of lung disease. The precision and repeatability of variable flip angle (VFA) T 1 mapping using modern 3D ultrashort echo time (UTE) imaging of the whole lung needs to be established before it can be used to assess response to disease and therapy. To evaluate the feasibility of regional lung T 1 quantification with VFA 3D-UTE and to investigate long- and short-term T 1 repeatability in the lungs of naive mice. Prospective preclinical animal study. Eight naive mice and phantoms. 3D free-breathing radial UTE (8 μs) at 4.7T. VFA 3D-UTE T 1 calculations were validated against T 1 values measured with inversion recovery (IR) in phantoms. Lung T 1 and proton density (S 0 ) measurements of whole lung and muscle were repeated five times over 1 month in free-breathing naive mice. Two consecutive T 1 measurements were performed during one of the imaging sessions. Agreement in T 1 between VFA 3D-UTE and IR in phantoms was assessed using Bland-Altman and Pearson 's correlation analysis. The T 1 repeatability in mice was evaluated using coefficient of variation (CV), repeated-measures analysis of variance (ANOVA), and paired t-test. Good T 1 agreement between the VFA 3D-UTE and IR methods was found in phantoms. T 1 in lung and muscle showed a 5% and 3% CV (1255 ± 63 msec and 1432 ± 42 msec, respectively, mean ± SD) with no changes in T 1 or S 0 over a month. Consecutive measurements resulted in an increase of 2% in both lung T 1 and S 0 . VFA 3D-UTE shows promise as a reliable T 1 mapping method that enables full lung coverage, high signal-to-noise ratio (∼25), and spatial resolution (300 μm) in freely breathing animals. The precision of the VFA 3D-UTE method will enable better design and powering of studies. 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018. © 2018 International Society for Magnetic Resonance in Medicine.

  6. Growth, morphological properties and pulsed photo response of MoTe2 single crystal synthesized by DVT technique

    Science.gov (United States)

    Dixit, Vijay; Vyas, Chirag; Patel, Abhishek; Pathak, V. M.; Solanki, G. K.; Patel, K. D.

    2018-05-01

    Molybednum Di Telluride of group VI belongs to the family of layered transition metal di-chalcogenides (TMDCs). These TMDCs show good potential for applications in the field of optoelectronic devices as they are chemically inert trilayered structure of MX2 type. In the present investigation crystals of MoTe2 are grown by direct vapor transport technique in a dual zone horizontal furnace. The grown crystals were characterized by Energy Dispersive Analysis of X-rays (EDAX) to study its elemental and stoichiometric composition, Selected Area Electron Diffraction (SAED) confirms the hexagonal structure. Spot pattern of electron diffraction shows formation of single phase. Scanning Electron Microscope (SEM) shows the layer by layer growth of the crystals, Thermo Electric Power (TEP) reflects the p-type semiconducting nature of the grown crystals. As this material is photosensitive material having band gap of approximately 1.0 eV, a transient photo response against polychromatic radiation (40 mW/cm2) of photodetector is also measured which showed slow decay in generated photocurrent due to low trapping density within the active area of the prepared device. Thus, it shows that this material can be a good photovoltaic material for constructing a solar cell also.

  7. Radial Ultrashort TE Imaging Removes the Need for Breath-Holding in Hepatic Iron Overload Quantification by R2* MRI.

    Science.gov (United States)

    Tipirneni-Sajja, Aaryani; Krafft, Axel J; McCarville, M Beth; Loeffler, Ralf B; Song, Ruitian; Hankins, Jane S; Hillenbrand, Claudia M

    2017-07-01

    The objective of this study is to evaluate radial free-breathing (FB) multiecho ultrashort TE (UTE) imaging as an alternative to Cartesian FB multiecho gradient-recalled echo (GRE) imaging for quantitative assessment of hepatic iron content (HIC) in sedated patients and subjects unable to perform breath-hold (BH) maneuvers. FB multiecho GRE imaging and FB multiecho UTE imaging were conducted for 46 test group patients with iron overload who could not complete BH maneuvers (38 patients were sedated, and eight were not sedated) and 16 control patients who could complete BH maneuvers. Control patients also underwent standard BH multiecho GRE imaging. Quantitative R2* maps were calculated, and mean liver R2* values and coefficients of variation (CVs) for different acquisitions and patient groups were compared using statistical analysis. FB multiecho GRE images displayed motion artifacts and significantly lower R2* values, compared with standard BH multiecho GRE images and FB multiecho UTE images in the control cohort and FB multiecho UTE images in the test cohort. In contrast, FB multiecho UTE images produced artifact-free R2* maps, and mean R2* values were not significantly different from those measured by BH multiecho GRE imaging. Motion artifacts on FB multiecho GRE images resulted in an R2* CV that was approximately twofold higher than the R2* CV from BH multiecho GRE imaging and FB multiecho UTE imaging. The R2* CV was relatively constant over the range of R2* values for FB multiecho UTE, but it increased with increases in R2* for FB multiecho GRE imaging, reflecting that motion artifacts had a stronger impact on R2* estimation with increasing iron burden. FB multiecho UTE imaging was less motion sensitive because of radial sampling, produced excellent image quality, and yielded accurate R2* estimates within the same acquisition time used for multiaveraged FB multiecho GRE imaging. Thus, FB multiecho UTE imaging is a viable alternative for accurate HIC assessment

  8. Measurement of the drift mobilities and the mobility-lifetime products of charge carriers in a CdZnTe crystal by using a transient pulse technique

    International Nuclear Information System (INIS)

    Cho, H Y; Kwon, Y K; Lee, C S; Lee, J H; Moon, J Y

    2011-01-01

    In this work we present results on the measurement of the drift mobility and the mobility-lifetime product of charge carriers in a 16-pixellated CdZnTe detector. For the determination of an interaction position based on the pulse rise-time method in a CZT detector, it is necessary to characterize the transport properties governed by drift mobility and lifetime for electrons and holes. In order to extract the transport properties of an electron and a hole, we bombarded 5.5-MeV alpha particles from a 241 Am source and 81-keV gamma rays emitted from a 133 Ba source on the negatively biased contact of the CZT detector. A time-of-flight (TOF) method was used to measure the electron drift mobility at room temperature whose value turned out to be 906.4 cm 2 /Vc s. With the Hecht's equation, the electron mobility-lifetime product was also determined from the bias-dependent alpha response and was equal to (9.88 ± 2.33) x 10 -3 cm 2 /V. On the other hand, the hole mobility-lifetime product was evaluated by a model based on the average charge collection efficiency which accounts for the absorption probability with a given photon energy. By using a single parameter fitting of the model, we obtained the hole mobility-lifetime product of (8.28 ± 0.17) x 10 -4 cm 2 /V.

  9. Effect of Low Temperature on a 4 W/60 K Pulse-Tube Cryocooler for Cooling HgCdTe Detector

    Science.gov (United States)

    Zhang, Ankuo; Liu, Shaoshuai; Wu, Yinong

    2018-04-01

    Temperature is an extremely important parameter for the material of the space-borne infrared detector. To cool an HgCdTe-infrared detector, a Stirling-type pulse-tube cryocooler (PTC) has been developed based on a great deal of numerical simulations, which are performed to investigate the thermodynamic behaviors of the PTC. The effects of different low temperatures are presented to analyze different energy flows, losses, phase shifts, and impedance matching of the PTC at a temperature range of 40-120 K, where woven wire screens are used. Finally, a high-efficiency coaxial PTC has been designed, built, and tested, operating around 60 K after a number of theoretical and experimental studies. The PTC can offer a no-load refrigeration temperature of 40 K with an input electric power of 150 W, and a cooling power of 4 W at 60 K is obtained with Carnot efficiency of 12%. In addition, a comparative study of simulation and experiment has been carried out, and some studies on reject temperatures have been presented for a thorough understanding of the PTC system.

  10. k-space sampling optimization for ultrashort TE imaging of cortical bone: Applications in radiation therapy planning and MR-based PET attenuation correction

    International Nuclear Information System (INIS)

    Hu, Lingzhi; Traughber, Melanie; Su, Kuan-Hao; Pereira, Gisele C.; Grover, Anu; Traughber, Bryan; Muzic, Raymond F. Jr.

    2014-01-01

    Purpose: The ultrashort echo-time (UTE) sequence is a promising MR pulse sequence for imaging cortical bone which is otherwise difficult to image using conventional MR sequences and also poses strong attenuation for photons in radiation therapy and PET imaging. The authors report here a systematic characterization of cortical bone signal decay and a scanning time optimization strategy for the UTE sequence through k-space undersampling, which can result in up to a 75% reduction in acquisition time. Using the undersampled UTE imaging sequence, the authors also attempted to quantitatively investigate the MR properties of cortical bone in healthy volunteers, thus demonstrating the feasibility of using such a technique for generating bone-enhanced images which can be used for radiation therapy planning and attenuation correction with PET/MR. Methods: An angularly undersampled, radially encoded UTE sequence was used for scanning the brains of healthy volunteers. Quantitative MR characterization of tissue properties, including water fraction and R2 ∗ = 1/T2 ∗ , was performed by analyzing the UTE images acquired at multiple echo times. The impact of different sampling rates was evaluated through systematic comparison of the MR image quality, bone-enhanced image quality, image noise, water fraction, and R2 ∗ of cortical bone. Results: A reduced angular sampling rate of the UTE trajectory achieves acquisition durations in proportion to the sampling rate and in as short as 25% of the time required for full sampling using a standard Cartesian acquisition, while preserving unique MR contrast within the skull at the cost of a minimal increase in noise level. The R2 ∗ of human skull was measured as 0.2–0.3 ms −1 depending on the specific region, which is more than ten times greater than the R2 ∗ of soft tissue. The water fraction in human skull was measured to be 60%–80%, which is significantly less than the >90% water fraction in brain. High-quality, bone

  11. Region specific optimization of continuous linear attenuation coefficients based on UTE (RESOLUTE)

    DEFF Research Database (Denmark)

    Ladefoged, Claes N; Benoit, Didier; Law, Ian

    2015-01-01

    The reconstruction of PET brain data in a PET/MR hybrid scanner is challenging in the absence of transmission sources, where MR images are used for MR-based attenuation correction (MR-AC). The main challenge of MR-AC is to separate bone and air, as neither have a signal in traditional MR images......-valued linear attenuation coefficients in bone that provides accurate reconstructed PET image data. A total of 164 [(18)F]FDG PET/MR patients were included in this study, of which 10 were used for training. MR-AC was based on either standard CT (reference), UTE or our method (RESOLUTE). The reconstructed PET...... on the reconstructed PET images, as well as limiting the number and extent of the outliers....

  12. Multicomponent Seismic Analysis and Calibration to Improve Recovery from Algal Mounds: Application to the Roadrunner/Towaoc area of the Paradox Basin, UTE Mountain UTE Reservation, Colorado

    International Nuclear Information System (INIS)

    Joe Hachey

    2007-01-01

    The goals of this project were: (1) To enhance recovery of oil contained within algal mounds on the Ute Mountain Ute tribal lands. (2) To promote the use of advanced technology and expand the technical capability of the Native American Oil production corporations by direct assistance in the current project and dissemination of technology to other Tribes. (3) To develop an understanding of multicomponent seismic data as it relates to the variations in permeability and porosity of algal mounds, as well as lateral facies variations, for use in both reservoir development and exploration. (4) To identify any undiscovered algal mounds for field-extension within the area of seismic coverage. (5) To evaluate the potential for applying CO 2 floods, steam floods, water floods or other secondary or tertiary recovery processes to increase production. The technical work scope was carried out by: (1) Acquiring multicomponent seismic data over the project area; (2) Processing and reprocessing the multicomponent data to extract as much geological and engineering data as possible within the budget and time-frame of the project; (3) Preparing maps and data volumes of geological and engineering data based on the multicomponent seismic and well data; (4) Selecting drilling targets if warranted by the seismic interpretation; (5) Constructing a static reservoir model of the project area; and (6) Constructing a dynamic history-matched simulation model from the static model. The original project scope covered a 6 mi 2 (15.6 km 2 ) area encompassing two algal mound fields (Towaoc and Roadrunner). 3D3C seismic data was to acquired over this area to delineate mound complexes and image internal reservoir properties such as porosity and fluid saturations. After the project began, the Red Willow Production Company, a project partner and fully-owned company of the Southern Ute Tribe, contributed additional money to upgrade the survey to a nine-component (3D9C) survey. The purpose of this upgrade

  13. Multicomponent Seismic Analysis and Calibration to Improve Recovery from Algal Mounds: Application to the Roadrunner/Towaoc area of the Paradox Basin, UTE Mountain UTE Reservation, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Joe Hachey

    2007-09-30

    The goals of this project were: (1) To enhance recovery of oil contained within algal mounds on the Ute Mountain Ute tribal lands. (2) To promote the use of advanced technology and expand the technical capability of the Native American Oil production corporations by direct assistance in the current project and dissemination of technology to other Tribes. (3) To develop an understanding of multicomponent seismic data as it relates to the variations in permeability and porosity of algal mounds, as well as lateral facies variations, for use in both reservoir development and exploration. (4) To identify any undiscovered algal mounds for field-extension within the area of seismic coverage. (5) To evaluate the potential for applying CO{sub 2} floods, steam floods, water floods or other secondary or tertiary recovery processes to increase production. The technical work scope was carried out by: (1) Acquiring multicomponent seismic data over the project area; (2) Processing and reprocessing the multicomponent data to extract as much geological and engineering data as possible within the budget and time-frame of the project; (3) Preparing maps and data volumes of geological and engineering data based on the multicomponent seismic and well data; (4) Selecting drilling targets if warranted by the seismic interpretation; (5) Constructing a static reservoir model of the project area; and (6) Constructing a dynamic history-matched simulation model from the static model. The original project scope covered a 6 mi{sup 2} (15.6 km{sup 2}) area encompassing two algal mound fields (Towaoc and Roadrunner). 3D3C seismic data was to acquired over this area to delineate mound complexes and image internal reservoir properties such as porosity and fluid saturations. After the project began, the Red Willow Production Company, a project partner and fully-owned company of the Southern Ute Tribe, contributed additional money to upgrade the survey to a nine-component (3D9C) survey. The purpose

  14. Geologic map of the Ute Mountain 7.5' quadrangle, Taos County, New Mexico, and Conejos and Costilla Counties, Colorado

    Science.gov (United States)

    Thompson, Ren A.; Turner, Kenzie J.; Shroba, Ralph R.; Cosca, Michael A.; Ruleman, Chester A.; Lee, John P.; Brandt, Theodore R.

    2014-01-01

    The Ute Mountain 7.5' quadrangle is located in the south-central part of the San Luis Basin of northern New Mexico, in the Rio Grande del Norte National Monument, and contains deposits that record volcanic, tectonic, and associated alluvial and colluvial processes over the past four million years. Ute Mountain has the distinction of being one of the largest intermediate composition eruptive centers of the Taos Plateau, a largely volcanic tableland occupying the southern portion of the San Luis Basin. Ute Mountain rises to an elevation in excess of 3,000 m, nearly 700 m above the basaltic plateau at its base, and is characterized by three distinct phases of Pliocene eruptive activity recorded in the stratigraphy exposed on the flanks of the mountain and in the Rio Grande gorge. Unconformably overlain by largely flat-lying lava flows of Servilleta Basalt, the area surrounding Ute Mountain records a westward thickening of basin-fill volcanic deposits interstratified in the subsurface with Pliocene basin-fill sedimentary deposits derived from older Tertiary and Precambrian sources to the east. Superimposed on this volcanic stratigraphy are alluvial and colluvial deposits derived from the flanks of Ute Mountain and more distally-derived alluvium from the uplifted Sangre de Cristo Mountains to the east, that record a complex temporal and stratigraphic succession of Quaternary basin deposition and erosion. Pliocene and younger basin deposition was accommodated along predominantly north-trending fault-bounded grabens. These poorly exposed fault scarps cutting lava flows of Ute Mountain volcano. The Servilleta Basalt and younger surficial deposits record largely down-to-east basinward displacement. Faults are identified with varying confidence levels in the map area. Recognizing and mapping faults developed near the surface in young, brittle volcanic rocks is difficult because: (1) they tend to form fractured zones tens of meters wide rather than discrete fault planes, (2

  15. UTE park group and other meso proterozoic units of the Nico Perez terrane: Rodina connecting

    International Nuclear Information System (INIS)

    Gaucher, C; Chemale, F.; Bossi, J.; Sial, A.; Chiglino, L.

    2010-01-01

    The Parque UTE Group is a volcano sedimentary succession metamorphosed in green schist facies, comprising (from base to top): the Canada Espinillo Formation (prasinites, pelites, andesite s), the Mina Valencia Formation (dolostones, limestones, marls) and the Cerro del Mast il Formation (black pelites, limestones, acid tuffs). Thickness of the GPU exceeds 2.5 km; base and top are not exposed. U-Pb zircon ages for basic magmatic rocks at the base and rhyolites at the top yielded 1492±4 and 1429±21 Ma, respectively. 13C values of carbonates of the Pug are characterized by a plateau at +1‰ VPDB, bracketed between two negative excursions.These values are consistent with an early Mesoproterozoic depositional age. Detrital zircon age spectra show that the source area of the GPU was the Nico Perez Terrane, being thus native to the Rio de la Plata Craton (Rpc). A Mesoproterozoic tectonic event at 1.25 Ga, recorded at both sides of the Sarandi del Yi mega shear, is discussed. New U-Pb zircon ages are presented for the La China Complex at its type area, where a schistosity N60W cuts the metamorphic banding and is parallel to thrusts dated K-Ar at 1253±32 Ma. The ages obtained are: 3096±45 Ma (main metamorphic event) and 1252 Ma (lower intercept). These data confirm the occurrence of a Grenvillian-aged tectonic event in Uruguay, suggesting that the RPC was part of the super continent Rodinia

  16. Phase diagrams of ZnTe-HgTe-Te and ZnTe-CdTe-HgTe-Te systems

    International Nuclear Information System (INIS)

    Andrukhiv, A.M.; Litvak, A.M.; Mironov, K.E.

    1992-01-01

    ZnTe-HgTe-Te system liquidus surface is investigated and solid solution layers are produced in this system by the method of liquid-phase epitaxy (LPE). The theoretical analysis of experimental and theoretical data allows to calculate the diagram of ZnTe-CdTe-HgTe-Te system fusibility. A significant effect of elastic stresses of the epitaxial layer, grown on CdTe substrate, on the process of LPE of solid solutions is established

  17. On the crystal structures of USe2, UTe2, ThOTe, and Er2Se3 - a contribution to the crystal chemistry of rare earth and actinide chalcogenides

    International Nuclear Information System (INIS)

    Dausch, W.M.

    1987-01-01

    The dichalcogenides of rare earth metals and actinides were classified into isostructural compounds without considering their composition. The structures of of α-USe 2 , β-USe 2 , UTe 2 , and HoSe 2 as well as of ThOTe, Er 2 Se 3 , and UTe 3 were determined by X-ray diffraction of their crystals. The results demonstrate that α-USe 2 has a SrBr 2 -analog structure and a stoichiometric composition. The atomic parameters derived from powder data of ThOTe and UTe 2 could be confirmed by X-ray analysis of the crystalline compounds. ThOTe crystallizes into a PbFCl-analog structure. The order of atoms in UTe 2 is similar to that of the ZrSe 3 type. The crystals of ErSe 3 , UTe 3 , HoSe 2 , and β-USe 2 were investigated only by camera methods. As in the case of Er 2 Se 3 or UTe 3 twin formation could be observed in β-USe 3 . (orig./RB) [de

  18. Airborne measurements of CO2 column concentrations made with a pulsed IPDA lidar using a multiple-wavelength-locked laser and HgCdTe APD detector

    Science.gov (United States)

    Abshire, James B.; Ramanathan, Anand K.; Riris, Haris; Allan, Graham R.; Sun, Xiaoli; Hasselbrack, William E.; Mao, Jianping; Wu, Stewart; Chen, Jeffrey; Numata, Kenji; Kawa, Stephan R.; Yang, Mei Ying Melissa; DiGangi, Joshua

    2018-04-01

    Here we report on measurements made with an improved CO2 Sounder lidar during the ASCENDS 2014 and 2016 airborne campaigns. The changes made to the 2011 version of the lidar included incorporating a rapidly wavelength-tunable, step-locked seed laser in the transmitter, using a much more sensitive HgCdTe APD detector and using an analog digitizer with faster readout time in the receiver. We also improved the lidar's calibration approach and the XCO2 retrieval algorithm. The 2014 and 2016 flights were made over several types of topographic surfaces from 3 to 12 km aircraft altitudes in the continental US. The results are compared to the XCO2 values computed from an airborne in situ sensor during spiral-down maneuvers. The 2014 results show significantly better performance and include measurement of horizontal gradients in XCO2 made over the Midwestern US that agree with chemistry transport models. The results from the 2016 airborne lidar retrievals show precisions of ˜ 0.7 parts per million (ppm) with 1 s averaging over desert surfaces, which is an improvement of about 8 times compared to similar measurements made in 2011. Measurements in 2016 were also made over fresh snow surfaces that have lower surface reflectance at the laser wavelengths. The results from both campaigns showed that the mean values of XCO2 retrieved from the lidar consistently agreed with those based on the in situ sensor to within 1 ppm. The improved precision and accuracy demonstrated in the 2014 and 2016 flights should benefit future airborne science campaigns and advance the technique's readiness for a space-based instrument.

  19. RF Pulsed Heating

    Energy Technology Data Exchange (ETDEWEB)

    Pritzkau, David P.

    2002-01-03

    RF pulsed heating is a process by which a metal is heated from magnetic fields on its surface due to high-power pulsed RF. When the thermal stresses induced are larger than the elastic limit, microcracks and surface roughening will occur due to cyclic fatigue. Pulsed heating limits the maximum magnetic field on the surface and through it the maximum achievable accelerating gradient in a normal conducting accelerator structure. An experiment using circularly cylindrical cavities operating in the TE{sub 011} mode at a resonant frequency of 11.424 GHz is designed to study pulsed heating on OFE copper, a material commonly used in normal conducting accelerator structures. The high-power pulsed RF is supplied by an X-band klystron capable of outputting 50 MW, 1.5 {micro}s pulses. The test pieces of the cavity are designed to be removable to allow testing of different materials with different surface preparations. A diagnostic tool is developed to measure the temperature rise in the cavity utilizing the dynamic Q change of the resonant mode due to heating. The diagnostic consists of simultaneously exciting a TE{sub 012} mode to steady-state in the cavity at 18 GHz and measuring the change in reflected power as the cavity is heated from high-power pulsed RF. Two experimental runs were completed. One run was executed at a calculated temperature rise of 120 K for 56 x 10{sup 6} pulses. The second run was executed at a calculated temperature rise of 82 K for 86 x 10{sup 6} pulses. Scanning electron microscope pictures show extensive damage occurring in the region of maximum temperature rise on the surface of the test pieces.

  20. The Ecological And Demographic Imperatives Of Land Fragmentation In Ute Districts of Vandeikya Local Government Area of Benue State, Nigeria

    Directory of Open Access Journals (Sweden)

    DANIEL SERKI ORTSERGA

    2014-04-01

    Full Text Available This study set out to investigate land fragmentation in Ute Districts of Vandeikya Local Government Area of Benue State in Nigeria with a view to gaining insight into its nature, extent and effect on the socio-economy of the area. To achieve this objective, 129 farm plots together with their owners were randomly selected and studied. Dimensions of individual plots and distances between plots and owners’ residences were determined through field measurements. A questionnaire survey was also conducted to obtain information on number of plots held per farming household in the area. In addition, aerial photographs taken over the area in 1977 and topographical maps of the area as well as reports were studied to get baseline data on the extent of fragmentation in the past. Analysis of data showed that, average size of farm plot in 1977 was 0.171 hectare, and declined to 0.149 hectare in 2009. Mean number of plots per farmer in 2009 was 5.37 and mean number of plots cultivated in the same year was 3.68, while range of plot holdings was between 2.67 and 10.00. Using Januszewski’s index of fragmentation, a value of 0.173 was derived, indicating extreme pulverization of farm plots in the area. It was also found that farm plots were not only small, but also scattered over space. The study noted the diseconomies of land fragmentation arising from its severe limitation on mechanization and input investment in farm enterprise. It however recommends support for fragmentation in the area as a realistic response to ecological and demographic imperatives and as a way of stabilizing the socio-economy. It also recommends diversification from agriculture to other gainful activities in the area to augment proceeds from the small and inappropriately distributed farm plots.

  1. FY 2000 report on the results of the advanced R and D for the UTES (underground thermal energy storage) system; 2000 nendo chichu jiban chikunetsu system gijutsu sendo kenkyu kaihatsu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-03-01

    In this study, study was made of the commercialization of the UTES (underground thermal energy storage) system using the underground heat source heat pump system technology as the base, considering that this is a technology suitable for the urban area where the heat demand intensively increases and a lot of exhaust heat and usable heat exist. By the realization of the UTES system technology, it is expected that the system promotes Japan's utilization of the unused energy and contributes to the construction of the CO2 emission control type society for Japan's energy policy and global warming prevention and secondarily to leveling of power loads and elimination of the heat island phenomenon in large cities. As to the UTES system which is aimed at being used for space heating and cooling and hot water supply in buildings, the following two were studied: the indirect system, BTES (borehole thermal energy storage) system, in which heat is collected/radiated from the ground by the heat exchanger installed underground; the direct system, ATES (aquifer thermal energy storage) system, in which the groundwater stored in aquifer is directly pumped up and used. The study was made in the items written below: 1) establishment of an system image of the UTES system; 2) evaluation study of effects of the introduction, practical applicability, etc. 3) extraction of the subjects for development. As a result, system images of the indirect/direct systems were obtained. (NEDO)

  2. FY 2000 report on the results of the advanced R and D for the UTES (underground thermal energy storage) system; 2000 nendo chichu jiban chikunetsu system gijutsu sendo kenkyu kaihatsu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-03-01

    In this study, study was made of the commercialization of the UTES (underground thermal energy storage) system using the underground heat source heat pump system technology as the base, considering that this is a technology suitable for the urban area where the heat demand intensively increases and a lot of exhaust heat and usable heat exist. By the realization of the UTES system technology, it is expected that the system promotes Japan's utilization of the unused energy and contributes to the construction of the CO2 emission control type society for Japan's energy policy and global warming prevention and secondarily to leveling of power loads and elimination of the heat island phenomenon in large cities. As to the UTES system which is aimed at being used for space heating and cooling and hot water supply in buildings, the following two were studied: the indirect system, BTES (borehole thermal energy storage) system, in which heat is collected/radiated from the ground by the heat exchanger installed underground; the direct system, ATES (aquifer thermal energy storage) system, in which the groundwater stored in aquifer is directly pumped up and used. The study was made in the items written below: 1) establishment of an system image of the UTES system; 2) evaluation study of effects of the introduction, practical applicability, etc. 3) extraction of the subjects for development. As a result, system images of the indirect/direct systems were obtained. (NEDO)

  3. Second harmonic generation in Te crystal using free electron laser

    CERN Document Server

    Yamauchi, T; Minehara, E J

    2002-01-01

    The second harmonic generation signal converted from the fundamental wavelength of 22 mu m of a free electron laser was observed for the first time using a birefringent Te crystal. The experimental conversion efficiency of Te crystal for second harmonic generation is 0.53%, which is equivalent to the theoretical value within a factor of 2. The Te crystal has been incorporated into an autocorrelator system to measure the micro-pulse width of infrared free electron laser successfully. (author)

  4. Pulse Generator

    Science.gov (United States)

    Greer, Lawrence (Inventor)

    2017-01-01

    An apparatus and a computer-implemented method for generating pulses synchronized to a rising edge of a tachometer signal from rotating machinery are disclosed. For example, in one embodiment, a pulse state machine may be configured to generate a plurality of pulses, and a period state machine may be configured to determine a period for each of the plurality of pulses.

  5. New MR pulse sequence

    International Nuclear Information System (INIS)

    Harms, S.E.; Flamig, D.P.; Griffey, R.H.

    1990-01-01

    This paper describes a method for fat suppression for three-dimensional MR imaging. The FATS (fat-suppressed acquisition with echo time shortened) sequence employs a pair of opposing adiabatic half-passage RF pulses tuned on fat resonance. The imaging parameters are as follows: TR, 20 msec; TE, 21.7-3.2 msec; 1,024 x 128 x 128 acquired matrix; imaging time, approximately 11 minutes. A series of 54 examinations were performed. Excellent fat suppression with water excitation is achieved in all cases. The orbital images demonstrate superior resolution of small orbital lesions. The high signal-to-noise ratio (SNR) in cranial studies demonstrates excellent petrous bone and internal auditory canal anatomy

  6. Fluctuations in induced charge introduced by Te inclusions within CdZnTe radiation detectors

    International Nuclear Information System (INIS)

    Bale, Derek S.

    2010-01-01

    Recently, homogenization theory based on a multiple-scale perturbation of the electron transport equation has been used to derive a mathematical framework for modeling the excess charge lost to Te inclusions within radiation detectors based on semi-insulating cadmium zinc telluride (CdZnTe). In that theory, the heterogeneous material is mathematically replaced by a homogenized CdZnTe crystal whose effective electron attenuation length incorporates the additional uniform electron trapping caused by the inclusions. In this paper, the homogenization theory is extended to incorporate fluctuations in the induced charge (i.e., charge collection nonuniformities) introduced by the random position and size distributions of a noncorrelated population of small (i.e, <20 μm) Te inclusions. Analysis of the effective parameters derived within the homogenized framework is used to develop a probability distribution of effective electron attenuation lengths, and therefore effective mobility-lifetime products, as a function of both the position and size distribution of Te inclusions. Example distributions are detailed for the case of an exponential size distribution at various number densities. Further, it is demonstrated that the inclusion-induced material nonuniformities derived in this paper can be numerically sampled efficiently, making them applicable to Monte Carlo device simulation of realistic CdZnTe detectors. Simulated charge induction maps and pulse-height spectra are presented and compared to recently published measurements.

  7. Hybrid Pulsed Nd:YAG Laser

    Science.gov (United States)

    Miller, Sawyer; Trujillo, Skyler; Fort Lewis College Laser Group Team

    This work concerns the novel design of an inexpensive pulsed Nd:YAG laser, consisting of a hybrid Kerr Mode Lock (KLM) and Q-switch pulse. The two pulse generation systems work independently, non simultaneously of each other, thus generating the ability for the user to easily switch between ultra-short pulse widths or large energy density pulses. Traditionally, SF57 glass has been used as the Kerr medium. In this work, novel Kerr mode-locking mediums are being investigated including: tellurite compound glass (TeO2), carbon disulfide (CS2), and chalcogenide glass. These materials have a nonlinear index of refraction orders of magnitude,(n2), larger than SF57 glass. The Q-switched pulse will utilize a Pockels cell. As the two pulse generation systems cannot be operated simultaneously, the Pockels cell and Kerr medium are attached to kinematic mounts, allowing for quick interchange between systems. Pulse widths and repetition rates will vary between the two systems. A goal of 100 picosecond pulse widths are desired for the mode-locked system. A goal of 10 nanosecond pulse widths are desired for the Q-switch system, with a desired repetition rate of 50 Hz. As designed, the laser will be useful in imaging applications.

  8. Pulse plating

    CERN Document Server

    Hansal, Wolfgang E G; Green, Todd; Leisner, Peter; Reichenbach, Andreas

    2012-01-01

    The electrodeposition of metals using pulsed current has achieved practical importance in recent years. Although it has long been known that changes in potential, with or without polarity reversal, can significantly affect the deposition process, the practical application of this has been slow to be adopted. This can largely be explained in terms of the complex relationship between the current regime and its effect on the electrodeposition process. In order to harness these effects, an understanding of the anodic and cathodic electrochemical processes is necessary, together with the effects of polarity reversal and the rate of such reversals. In this new monograph, the basics of metal electrodeposition from solution are laid out in great detail in seven distinct chapters. With this knowledge, the reader is able to predict how a given pulse train profile can be adopted to achieve a desired outcome. Equally important is the choice of a suitable rectifier and the ancillary control circuits to enable pulse platin...

  9. HIGH SPATIAL-RESOLUTION IMAGING OF TE INCLUSIONS IN CZT MATERIAL

    International Nuclear Information System (INIS)

    CAMARDA, G.S.; BOLOTNIKOV, A.E.; CARINI, G.A.; CUI, Y.; KOHMAN, K.T.; LI, L.; JAMES, R.B.

    2006-01-01

    We present new results from our studies of defects in current single-crystal CdZnTe material. Our previous measurements, carried out on thin (∼1 mm) and long (>12 mm) CZT detectors, indicated that small (1-20 (micro)m) Te inclusions can significantly degrade the device's energy resolution and detection efficiency. We are conducting detailed studies of the effects of Te inclusions by employing different characterization techniques with better spatial resolution, such as quantitative fluorescence mapping, X-ray micro-diffraction, and TEM. Also, IR microscopy and gamma-mapping with pulse-shape analysis with higher spatial resolution generated more accurate results in the areas surrounding the micro-defects (Te inclusions). Our results reveal how the performance of CdZnTe detectors is influenced by Te inclusions, such as their spatial distribution, concentration, and size. We also discuss a model of charge transport through areas populated with Te inclusions

  10. Controllable SET process in O-Ti-Sb-Te based phase change memory for synaptic application

    Science.gov (United States)

    Ren, Kun; Li, Ruiheng; Chen, Xin; Wang, Yong; Shen, Jiabin; Xia, Mengjiao; Lv, Shilong; Ji, Zhenguo; Song, Zhitang

    2018-02-01

    The nonlinear resistance change and small bit resolution of phase change memory (PCM) under identical operation pulses will limit its performance as a synaptic device. The octahedral Ti-Te units in Ti-Sb-Te, regarded as nucleation seeds, are degenerated when Ti is bonded with O, causing a slower crystallization and a controllable SET process in PCM cells. A linear resistance change under identical pulses, a resolution of ˜8 bits, and an ON/OFF ratio of ˜102 has been achieved in O-Ti-Sb-Te based PCM, showing its potential application as a synaptic device to improve recognition performance of the neural network.

  11. Pulsed power

    International Nuclear Information System (INIS)

    Anon.

    1977-01-01

    The key element of our pulsed power program is concentration of power in time and space by suppression of breakdown in dielectrics and in vacuum. Magnetically insulated vacuum transmission lines and magnetic suppression of insulator flashover have continued as the main reserch directions. Vacuum insulated line studies at Physics International have been expanded and a test bed at Sandia, called MITE (Magnetically Insulated Transmission Experiment), is under development. The choice for the baseline EBFA design will depend on the outcome of these studies and should be made in July 1977. The slow and intermediate speed pulsed power approaches to EBFA will be based on Proto I and Proto II results and several of the projected EBFA subsystems are presently being tested in Proto II. A further stage of power concentration, within the vacuum diode itself, would considerably ease the burden on dielectrics; methods of power multiplication involving magnetically imploded plasmas are being considered and tests have begun using the Ripple III apparatus

  12. AsTeRICS.

    Science.gov (United States)

    Drajsajtl, Tomáš; Struk, Petr; Bednárová, Alice

    2013-01-01

    AsTeRICS - "The Assistive Technology Rapid Integration & Construction Set" is a construction set for assistive technologies which can be adapted to the motor abilities of end-users. AsTeRICS allows access to different devices such as PCs, cell phones and smart home devices, with all of them integrated in a platform adapted as much as possible to each user. People with motor disabilities in the upper limbs, with no cognitive impairment, no perceptual limitations (neither visual nor auditory) and with basic skills in using technologies such as PCs, cell phones, electronic agendas, etc. have available a flexible and adaptable technology which enables them to access the Human-Machine-Interfaces (HMI) on the standard desktop and beyond. AsTeRICS provides graphical model design tools, a middleware and hardware support for the creation of tailored AT-solutions involving bioelectric signal acquisition, Brain-/Neural Computer Interfaces, Computer-Vision techniques and standardized actuator and device controls and allows combining several off-the-shelf AT-devices in every desired combination. Novel, end-user ready solutions can be created and adapted via a graphical editor without additional programming efforts. The AsTeRICS open-source framework provides resources for utilization and extension of the system to developers and researches. AsTeRICS was developed by the AsTeRICS project and was partially funded by EC.

  13. PULSE COLUMN

    Science.gov (United States)

    Grimmett, E.S.

    1964-01-01

    This patent covers a continuous countercurrent liquidsolids contactor column having a number of contactor states each comprising a perforated plate, a layer of balls, and a downcomer tube; a liquid-pulsing piston; and a solids discharger formed of a conical section at the bottom of the column, and a tubular extension on the lowest downcomer terminating in the conical section. Between the conical section and the downcomer extension is formed a small annular opening, through which solids fall coming through the perforated plate of the lowest contactor stage. This annular opening is small enough that the pressure drop thereacross is greater than the pressure drop upward through the lowest contactor stage. (AEC)

  14. Pulse radiolysis

    International Nuclear Information System (INIS)

    Greenshields, H.; Seddon, W.A.

    1982-03-01

    This supplement to two bibliographies published in 1970 and 1972 lists 734 references to the literature of pulse radiolysis, arranged under eight broad subject headings. The references were compiled by searching Biological Abstracts, Chemical Abstracts, Nuclear Science Abstracts and the Weekly List of Papers in Radiation Chemistry issued by the Radiation Chemistry Data Center of Notre Dame University. Full bibliographic data is given for papers published in the period 1971 to 1974. A personal author index listing more than 600 authors and a similar number of co-authors is included

  15. Structure of Se-Te glasses studied using neutron, X-ray diffraction and reverse Monte Carlo modelling

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Keiji, E-mail: itoh@okayama-u.ac.jp [Graduate School of Education, Okayama University, Tsushima-naka, Okayama 700-8530 (Japan); Research Reactor Institute, Kyoto University, Kumatori, Osaka 590-0494 (Japan)

    2017-02-15

    Pulsed neutron diffraction and synchrotron X-ray diffraction measurements were performed on Se{sub 100-x}Te{sub x} bulk glasses with x=10, 20, 30 and 40. The coordination numbers obtained from the diffraction results demonstrate that Se and Te atoms are twofold coordinated and the glass structure is formed by the chain network. The three-dimensional structure model for Se{sub 60}Te{sub 40} glass obtained by using reverse Monte Carlo modelling shows that the alternating arrangements of Se and Te atoms compose the major part of the chain clusters but several other fragments such as Se{sub n} chains and Te-Te dimers are also present in large numbers. The chain clusters have geometrically disordered forms and the interchain atomic order is different from those in the crystal structures of trigonal Se and trigonal Te. - Graphical abstract: Coordination environment in Se{sub 60}Te{sub 40} glass.

  16. Pulse pile-up. I: Short pulses

    International Nuclear Information System (INIS)

    Wilkinson, D.H.

    1990-07-01

    The search for rare large pulses against an intense background of smaller ones involves consideration of pulse pile-up. Approximate methods are presented, based on ruin theory, by which the probability of such pile-up may be estimated for pulses of arbitrary form and of arbitrary pulse-height distribution. These methods are checked against cases for which exact solutions are available. The present paper is concerned chiefly with short pulses of finite total duration. (Author) (5 refs., 24 figs.)

  17. Reduced field TE01 X-Band traveling wave window

    International Nuclear Information System (INIS)

    Fowkes, W.R.; Callin, R.S.; Tantawi, S.G.; Wright, E.L.

    1995-01-01

    The RF electric field is reduced by more than a factor of two using a pair of symmetrically located irises in a new type of klystron window operating in the TE 01 mode at X-Band. The advantages of this window over the usual TE 01 half-wave resonant window are discussed as well as theory and operating results. Ultra high purity alumina formed by the HIP process is used. This window has been successfully tested at 100 MW with a 1.5 microsecond RF pulse width and is being used on the XL series klystrons

  18. A short TE gradient-echo sequence using asymmetric sampling

    International Nuclear Information System (INIS)

    Fujita, Norihiko; Harada, Kohshi; Sakurai, Kosuke; Nakanishi, Katsuyuki; Kim, Shyogen; Kozuka, Takahiro

    1990-01-01

    We have developed a gradient-echo pulse sequence with a short TE less than 4 msec using a data set of asymmetric off-center sampling with a broad bandwidth. The use of such a short TE significantly reduces T 2 * dephasing effect even in a two-dimensional mode, and by collecting an off-center echo, motion-induced phase dispersion is also considerably decreased. High immunity of this sequence to these dephasing effects permits clear visualization of anatomical details near the skull base where large local field inhomogeneities and rapid blood flow such as in the internal carotid artery are present. (author)

  19. Experimental study of pulsed heating of electromagnetic cavities

    International Nuclear Information System (INIS)

    Pritzkau, D.P.; Menegat, A.; Siemann, R.H.

    1997-01-01

    An experiment to study the effects of pulsed heating in electromagnetic cavities will be performed. Pulsed heating is believed to be the limiting mechanism of high acceleration gradients at short wavelengths. A cylindrical cavity operated in the TE 011 mode at a frequency of 11.424 GHz will be used. A klystron will be used to supply a peak input power of 20 MW with a pulse length of 1.5 μs. The temperature response of the cavity will be measured by a second waveguide designed to excite a TE 012 mode in the cavity with a low-power CW signal at a frequency of 17.8 GHz. The relevant theory of pulsed heating will be discussed and the results from cold-testing the structure will be presented

  20. Ga-Bi-Te system

    International Nuclear Information System (INIS)

    Rustamov, P.G.; Seidova, N.A.; Shakhbazov, M.G.; AN Azerbajdzhanskoj SSR, Baku. Inst. Neorganicheskoj i Fizicheskoj Khimii)

    1976-01-01

    To elucidate the nature of interaction in the system Ga-Bi-Te, a study has been made of sections GaTe-Bi 2 Te 3 , Ga 2 Te 3 -Bi, GaTe-Bi and Bi 2 Te 3 -Ga. The alloys have been prepared by direct melting of the components or their alloys with subsequent homogenizin.o annealing at 400 deg C. The study has been made by the methods of differential thermal, microstructural analysis and by microhardness measurements. On the basis of literature data and data obtained a projection of the liquidus surface of the phase diagram for the system Ga-Bi-Te has been constructed. In the ternary system there are 17 curves of monovariant equilibrium dividing the liquidus into 10 fields of primary crystallization of phases, 9 points of non-variant equilibrium of which 4 points are triple eutectics and 5 points are triple peritectics

  1. A simple optical spectral calibration technique for pulsed THz sources

    NARCIS (Netherlands)

    Wijnen, F.J.P.; G. Berden,; Jongma, R.T.

    2010-01-01

    We have quantified the sensitivity of a simple method to measurethe frequency spectrum of pulsed terahertz (THz) radiation. The THzpulses are upconverted to the optical regime by sideband generation in a zinctelluride (ZnTe) crystal using a continuous wave (cw) narrow-bandwidthnear-infrared laser. A

  2. Random pulse generator

    International Nuclear Information System (INIS)

    Guo Ya'nan; Jin Dapeng; Zhao Dixin; Liu Zhen'an; Qiao Qiao; Chinese Academy of Sciences, Beijing

    2007-01-01

    Due to the randomness of radioactive decay and nuclear reaction, the signals from detectors are random in time. But normal pulse generator generates periodical pulses. To measure the performances of nuclear electronic devices under random inputs, a random generator is necessary. Types of random pulse generator are reviewed, 2 digital random pulse generators are introduced. (authors)

  3. Growth And Characterization Of LPE CdHgTe/CdZnTe/CdZnTe Structure

    Science.gov (United States)

    Pelliciari, B.; Chamonal, J. P.; Destefanis, G. L.; Dicioccio, L.

    1988-05-01

    The liquid phase epitaxial technique is used to grow Hgl_x Cdx Te (x = .23) from a Te - rich solution onto a Cdl_y ZnyTe (y = .04) buffer layer grown from a Te-rich solution onto a Cdi_yZnyTe bulk substrate in an open tube multibin horizontal slider apparatus.Growth conditions and physical characterizations of both the buffer layer and the CdHgTe layer are given ; electrical properties of the CdHgTe layer are also presen-ted. PV detectors were successfully obtained on such a structure using an ion-implanted technology and their characteristics at 77 K for a 10.1 ,um cut-off wavelength are given.

  4. Programmable pulse generator

    International Nuclear Information System (INIS)

    Xue Zhihua; Lou Binqiao; Duan Xiaohui

    2002-01-01

    The author introduces the design of programmable pulse generator that is based on a micro-controller and controlled by RS232 interface of personal computer. The whole system has good stability. The pulse generator can produce TTL pulse and analog pulse. The pulse frequency can be selected by EPLD. The voltage amplitude and pulse width of analog pulse can be adjusted by analog switches and digitally-controlled potentiometers. The software development tools of computer is National Instruments LabView5.1. The front panel of this virtual instrumentation is intuitive and easy-to-use. Parameters can be selected and changed conveniently by knob and slide

  5. Pulsed water jet generated by pulse multiplication

    Czech Academy of Sciences Publication Activity Database

    Dvorský, R.; Sitek, Libor; Sochor, T.

    2016-01-01

    Roč. 23, č. 4 (2016), s. 959-967 ISSN 1330-3651 R&D Projects: GA MŠk(CZ) LO1406; GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : high- pressure pulses * pulse intensifier * pulsed water jet * water hammer effect Subject RIV: JQ - Machines ; Tools Impact factor: 0.723, year: 2016 http://hrcak.srce.hr/163752?lang=en

  6. Effect of adding Cr on magnetic properties and metallic behavior in MnTe film

    International Nuclear Information System (INIS)

    Wang, Z.H.; Geng, D.Y.; Gong, W.J.; Li, J.; Li, Y.B.; Zhang, Z.D.

    2012-01-01

    Mn 1−x Cr x Te films with x = 0, 0.02, and 0.05 was synthesized by pulsed laser deposition and crystallize in hexagonal NiAs-type structure. The spin glass behavior predicted before by Monte Carlo calculation is observed in the MnTe film. This behavior is destroyed by adding Cr in the MnTe film. The temperature dependence of magnetization shows a sharp rise at around 66 K, due to the magneto-elastic coupling. Metallic behavior is observed in the MnTe film in the temperature range 120–220 K, which is ascribed to the magnetic ordering. The metallic behavior disappears with adding Cr, because adding Cr ions destroys the magnetic ordering which is mediated by the sp–d exchange interaction between the Cr ions. - Highlights: ► Mn 1−x Cr x Te films with NiAs-type structure was prepared by pulsed laser deposition. ► The spin glass behavior was observed in MnTe film at low temperature. ► The spin glass behavior was destroyed by adding Cr. ► The temperature dependence of magnetization showed a sharp rise at around 66 K. ► Metallic behavior was observed in MnTe film, which disappeared by adding Cr.

  7. ADVANCED READOUT ELECTRONICS FOR MULTIELEMENT CdZnTe SENSORS

    International Nuclear Information System (INIS)

    DE GERONIMO, G.; O CONNOR, P.; KANDASAMY, A.; GROSHOLZ, J.

    2002-01-01

    A generation of high performance front-end and read-out ASICs customized for highly segmented CdZnTe sensors is presented. The ASICs, developed in a multi-year effort at Brookhaven National Laboratory, are targeted to a wide range of applications including medical, safeguards/security, industrial, research, and spectroscopy. The front-end multichannel ASICs provide high accuracy low noise preamplification and filtering of signals, with versions for small and large area CdZnTe elements. They implement a high order unipolar or bipolar shaper, an innovative low noise continuous reset system with self-adapting capability to the wide range of detector leakage currents, a new system for stabilizing the output baseline and high output driving capability. The general-purpose versions include programmable gain and peaking time. The read-out multichannel ASICs provide fully data driven high accuracy amplitude and time measurements, multiplexing and time domain derandomization of the shaped pulses. They implement a fast arbitration scheme and an array of innovative two-phase offset-free rail-to-rail analog peak detectors for buffering and absorption of input rate fluctuations, thus greatly relaxing the rate requirement on the external ADC. Pulse amplitude, hit timing, pulse risetime, and channel address per processed pulse are available at the output in correspondence of an external readout request. Prototype chips have been fabricated in 0.5 and 0.35 (micro)m CMOS and tested. Design concepts and experimental results are discussed

  8. Selenium Se and tellurium Te

    International Nuclear Information System (INIS)

    Busev, A.I.; Tiptsova, V.G.; Ivanov, V.M.

    1978-01-01

    The basic methods for determining selenium and tellurium in various objects are presented. The bichromatometric determination of Te in cadmium, zinc and mercury tellurides is based on oxidation of Te(4) to (6) in H 2 SO 4 with potassium bichromate. In steels, Te is determined photometrically with the aid of KI. The determination is hindered by Fe(3), Cu(2), Bi(3) and Se(4) ions, which must be separated. The extraction-photometric determination of Te in native sulfur is carried out with the aid of 5-mercapto-3-(naphthyl-2)-1,3,4-thiadiazolthione-2 (pH=4.8-5.0). The dyed complex is readily extracted with chloroform and benzene. The spectrophotometric determination of Te in selenium is performed with the aid of 3,5-diphenylpyrazoline-1-dithiocarbamate of sodium. Te is determined in commercial indium, arsenic and their semiconductor compounds photometrically with the aid of copper diethyldithiocarbamate. The method permits determining 5x10 -5 % Te in a weighed amount of 0.5 g. The chloride complex of Te(4) with diantipyriodolpropylmethane is quantitatively extracted with dichloroethane from hydrochloric acid solutions. Thus, any amounts of Te can be separated from Se and determined photometrically. The extraction-photometric determination of Te in commercial lead and bismuth is carried out with the aid of pyrazolone derivatives, in commercial copper with the aid of diantipyridolpropylmethane, and in ores (more than 0.01% Te) with the aid of bismuthol 2. Also described is the extraction-polarographic determination of Te in sulfide ores

  9. Laser pulse stacking method

    Science.gov (United States)

    Moses, E.I.

    1992-12-01

    A laser pulse stacking method is disclosed. A problem with the prior art has been the generation of a series of laser beam pulses where the outer and inner regions of the beams are generated so as to form radially non-synchronous pulses. Such pulses thus have a non-uniform cross-sectional area with respect to the outer and inner edges of the pulses. The present invention provides a solution by combining the temporally non-uniform pulses in a stacking effect to thus provide a more uniform temporal synchronism over the beam diameter. 2 figs.

  10. Te/C nanocomposites for Li-Te Secondary Batteries

    Science.gov (United States)

    Seo, Jeong-Uk; Seong, Gun-Kyu; Park, Cheol-Min

    2015-01-01

    New battery systems having high energy density are actively being researched in order to satisfy the rapidly developing market for longer-lasting mobile electronics and hybrid electric vehicles. Here, we report a new Li-Te secondary battery system with a redox potential of ~1.7 V (vs. Li+/Li) adapted on a Li metal anode and an advanced Te/C nanocomposite cathode. Using a simple concept of transforming TeO2 into nanocrystalline Te by mechanical reduction, we designed an advanced, mechanically reduced Te/C nanocomposite electrode material with high energy density (initial discharge/charge: 1088/740 mA h cm-3), excellent cyclability (ca. 705 mA h cm-3 over 100 cycles), and fast rate capability (ca. 550 mA h cm-3 at 5C rate). The mechanically reduced Te/C nanocomposite electrodes were found to be suitable for use as either the cathode in Li-Te secondary batteries or a high-potential anode in rechargeable Li-ion batteries. We firmly believe that the mechanically reduced Te/C nanocomposite constitutes a breakthrough for the realization and mass production of excellent energy storage systems.

  11. Aardkastanje, onopvallend en te weinig om te eten

    NARCIS (Netherlands)

    Spruijt, T.

    2010-01-01

    Hij staat vanaf half juni volop in bloei, maar wordt door weinigen gezien. Hoewel een zoektocht op Google anders doet vermoeden, wordt hij niet meer gegeten. De Aardkastanje is daarvoor te onopvallend en te zeldzaam in Nederland. Toch is het een bijzondere schermbloem.

  12. Pulse to pulse klystron diagnosis system

    International Nuclear Information System (INIS)

    Nowak, J.; Davidson, V.; Genova, L.; Johnson, R.; Reagan, D.

    1981-03-01

    This report describes a system used to study the behavior of SLAC high powered klystrons operating with a twice normal pulse width of 5 μs. At present, up to eight of the klystrons installed along the accelerator can be operated with long pulses and monitored by this system. The report will also discuss some of the recent findings and investigations

  13. PbTe mechanosynthesis from PbO and Te

    International Nuclear Information System (INIS)

    Rojas-Chavez, Hugo; Diaz-de la Torre, Sebastian; Jaramillo-Vigueras, David; Plascencia, Gabriel

    2009-01-01

    Experimental results concerning the mechanosynthesis (MSY), of PbTe from the PbO-Te powder system, at room temperature an atmospheric conditions are reported. XRD results for samples milled for and after 5.4 ks only show PbTe diffraction peaks; neither Te nor PbO or any other solid phase were detected. Particle size and morphology, was followed by SEM observations. Phase evolution and quantification was monitored by Rietveld refinements of the X-ray diffraction data. It was found that the use of lead oxide as a component of the mechanosynthesis system reduces milling time with respect to the Pb-Te metallic system with mechanical alloying.

  14. Influence of the additive Ag for crystallization of amorphous Ge-Sb-Te thin films

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ki-Ho; Kim, Sung-Won; Seo, Jae-Hee [Faculty of Applied Chemical Engineering, Chonnam National University, 300 Yongbong-dong, Kwangju 500-757 (Korea, Republic of); Lee, Hyun-Yong, E-mail: hyleee@chonnam.ac.k [Faculty of Applied Chemical Engineering, Chonnam National University, 300 Yongbong-dong, Kwangju 500-757 (Korea, Republic of)

    2009-05-29

    We have investigated the optical and amorphous-to-crystalline transition properties in four-types of chalcogenide thin films; Ge{sub 2}Sb{sub 2}Te{sub 5}, Ge{sub 8}Sb{sub 2}Te{sub 11}, Ag-Ge{sub 2}Sb{sub 2}Te{sub 5} and Ag-Ge{sub 8}Sb{sub 2}Te{sub 11}. Crystallization was caused by nano-pulse illumination ({lambda} = 658 nm) with power (P) of 1-17 mW and pulse duration (t) of 10-460 ns, and the morphologies of crystallized spots were observed by SEM and microscope. It was found that the crystallized spot nearby linearly increases in size with increasing the illuminating energy (E = P {center_dot} t) and eventually ablated out by over illumination. Changes in the optical transmittance of as-deposited and annealed films were measured using a UV-vis-IR spectrophotometer. In addition, a speed of amorphous-to-crystalline transition was evaluated by detecting the reflection response signals for the nano-pulse scanning. Conclusively, the Ge{sub 8}Sb{sub 2}Te{sub 11} film has a faster crystallization speed than the Ge{sub 2}Sb{sub 2}Te{sub 5} film despite its higher crystallization temperature. The crystallization speed was largely improved by adding Ag in Ge{sub 2}Sb{sub 2}Te{sub 5} film but not in Ge{sub 8}Sb{sub 2}Te{sub 11} film. To explain these results, we considered a heat confinement by electron hopping.

  15. The quadrupole interaction of 125Te and 129I in polycrystalline Te and in Te single crystals

    International Nuclear Information System (INIS)

    Langouche, G.; Rossum, M. van; Schmidt, K.P.; Coussement, R.

    1975-01-01

    Single crystals as hosts for Te and I sources were used in a study of Te. The Moessbauer spectra of 125 Te and 129 I in polycrystalline Te at liquid He temperature are given. Also presented are the Moessbauer spectra of 125 Te in a Te single crystal for the gamma ray parallel to the c-axis and perpendicular to the c-axis of the crystal at liquid He temperature. (Z.S.)

  16. La Zona del Carbón durante el gobierno de la Unidad Popular y la Educación de los Trabajadores: Sedes universitarias UdeC-UTE de 1971

    Directory of Open Access Journals (Sweden)

    Ismael Cáceres-Correa

    2013-07-01

    Full Text Available Resumen: Durante el Gobierno de la Unidad Popular en Chile se materializaron una serie de demandas populares que exigían cada día mayores cuotas de mandato en los distintos ámbitos de la sociedad. Una de ellas fue la exigencia de una mejora en la educación de los trabajadores de la  Zona del Carbón para desarrollar con mayor acierto sus funciones laborales. Durante años esta demanda se había incubado en la idea de los sindicatos y autoridades de  la  Zona  provocando que  en  1971  se  unieran las  Universidades de Concepción y Técnica del Estado para llevar a cabo un proyecto educativo y político en el mencionado sector. El texto busca dar cuenta de este hecho concreto y contrastar su olvido intencionado a través de la memoria de quienes vivieron el proceso. Palabras clave: UdeC, UTE, carbón, educación con adultos, educación de trabajadores, Coronel-Lota

  17. Bouwlogistieke innovaties weerbarstig te implementeren

    NARCIS (Netherlands)

    Ludema, M.W.; Vries, A.M.R.

    2015-01-01

    Toelevering van bouwmaterialen aan bouwprojecten is complex en verregaande gesegregeerd. De bouwsector staat voor een kans te innoveren op het vlak van de bouwlogistiek. In het verleden is ervaring opgedaan met ‘best-practices’ die voldoende kansen bieden de noodzakelijk innovatie door te voeren.

  18. 34 GHz, 45 MW pulsed magnicon

    International Nuclear Information System (INIS)

    Nezhevenko, Oleg A.; LaPointe, Michael A.; Yakovlev, Vyacheslav P.; Hirshfield, Jay L.; Serdobintsev, Gennady V.; Kuznetsov, Gennady I.; Persov, Boris Z.; Fix, Alexander

    2002-01-01

    A high efficiency, high power magnicon at 34.272 GHz has been designed and built as a microwave source to develop RF technology for a future multi-TeV electron-positron linear collider. The tube is designed to provide a peak output power of ∼45 MW in a 1 microsecond pulse, with a gain of 55 dB, using a 500 kV, 220 A, 1 mm-diameter electron beam. The status of the tube itself as well as the near-term experimental program is presented

  19. Cs-K-Te photo cathodes: a promising electron source for free-electron lasers

    NARCIS (Netherlands)

    Bisero, D.; Bisero, D.; van Oerle, B.M.; van Oerle, B.M.; Ernst, G.J.; Verschuur, Jeroen W.J.; Witteman, W.J.

    1998-01-01

    The characteristics of Cs–K–Te photo-cathodes when used in a photo-cathode linear accelerator will be presented together with a short review of their photo-emissive properties. The cathodes have been illuminated by light pulses obtained by frequency quadrupling the light of a Nd:YLF laser. The

  20. Epitaxial growth of Ge-Sb-Te based phase change materials

    Energy Technology Data Exchange (ETDEWEB)

    Perumal, Karthick

    2013-07-30

    Ge-Sb-Te based phase change materials are considered as a prime candidate for optical and electrical data storage applications. With the application of an optical or electrical pulse, they can be reversibly switched between amorphous and crystalline state, thereby exhibiting large optical and electrical contrast between the two phases, which are then stored as information in the form of binary digits. Single crystalline growth is interesting from both the academic and industrial perspective, as ordered Ge-Sb-Te based metamaterials are known to exhibit switching at reduced energies. The present study deals with the epitaxial growth and analysis of Ge-Sb-Te based thin films. The first part of the thesis deals with the epitaxial growth of GeTe. Thin films of GeTe were grown on highly mismatched Si(111) and (001) substrates. On both the substrate orientations the film grows along [111] direction with an amorphous-to-crystalline transition observed during the initial stages of growth. The amorphous-to-crystalline transition was studied in-vivo using azimuthal reflection high-energy electron diffraction scans and grazing incidence X-ray diffraction. In the second part of the thesis epitaxy and characterization of Sb{sub 2}Te{sub 3} thin films are presented. The third part of the thesis deals with the epitaxy of ternary Ge-Sb-Te alloys. The composition of the films are shown to be highly dependent on growth temperatures and vary along the pseudobinary line from Sb{sub 2}Te{sub 3} to GeTe with increase in growth temperatures. A line-of-sight quadrupole mass spectrometer was used to reliably control the GeSbTe growth temperature. Growth was performed at different Ge, Sb, Te fluxes to study the compositional variation of the films. Incommensurate peaks are observed along the [111] direction by X-ray diffraction. The possibility of superstructural vacancy ordering along the [111] direction is discussed.

  1. Epitaxial growth of Ge-Sb-Te based phase change materials

    International Nuclear Information System (INIS)

    Perumal, Karthick

    2013-01-01

    Ge-Sb-Te based phase change materials are considered as a prime candidate for optical and electrical data storage applications. With the application of an optical or electrical pulse, they can be reversibly switched between amorphous and crystalline state, thereby exhibiting large optical and electrical contrast between the two phases, which are then stored as information in the form of binary digits. Single crystalline growth is interesting from both the academic and industrial perspective, as ordered Ge-Sb-Te based metamaterials are known to exhibit switching at reduced energies. The present study deals with the epitaxial growth and analysis of Ge-Sb-Te based thin films. The first part of the thesis deals with the epitaxial growth of GeTe. Thin films of GeTe were grown on highly mismatched Si(111) and (001) substrates. On both the substrate orientations the film grows along [111] direction with an amorphous-to-crystalline transition observed during the initial stages of growth. The amorphous-to-crystalline transition was studied in-vivo using azimuthal reflection high-energy electron diffraction scans and grazing incidence X-ray diffraction. In the second part of the thesis epitaxy and characterization of Sb 2 Te 3 thin films are presented. The third part of the thesis deals with the epitaxy of ternary Ge-Sb-Te alloys. The composition of the films are shown to be highly dependent on growth temperatures and vary along the pseudobinary line from Sb 2 Te 3 to GeTe with increase in growth temperatures. A line-of-sight quadrupole mass spectrometer was used to reliably control the GeSbTe growth temperature. Growth was performed at different Ge, Sb, Te fluxes to study the compositional variation of the films. Incommensurate peaks are observed along the [111] direction by X-ray diffraction. The possibility of superstructural vacancy ordering along the [111] direction is discussed.

  2. CdTe as a passivating layer in CdTe/HgCdTe heterostructures

    International Nuclear Information System (INIS)

    Virt, I. S.; Kurilo, I. V.; Rudyi, I. A.; Sizov, F. F.; Mikhailov, N. N.; Smirnov, R. N.

    2008-01-01

    CdTe/Hg 1-x Cd x Te heterostructures are studied. In the structures, CdTe is used as a passivating layer deposited as a polycrystal or single crystal on a single-crystal Hg 1-x Cd x Te film. The film and a passivating layer were obtained in a single technological process of molecular beam epitaxy. The structure of passivating layers was studied by reflection high-energy electron diffraction, and the effect of the structure of the passivating layer on the properties of the active layer was studied by X-ray diffractometry. Mechanical properties of heterostructures were studied by the microhardness method. Electrical and photoelectrical parameters of the Hg 1-x Cd x Te films are reported.

  3. Morphological analysis of GeTe in inline phase change switches

    Energy Technology Data Exchange (ETDEWEB)

    King, Matthew R., E-mail: matthew.king2@ngc.com [Northrop Grumman Electronic Systems, Advanced Concepts and Technologies Division, 1212 Winterson Rd., Linthicum, Maryland 21090 (United States); Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); El-Hinnawy, Nabil [Northrop Grumman Electronic Systems, Advanced Concepts and Technologies Division, 1212 Winterson Rd., Linthicum, Maryland 21090 (United States); Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Salmon, Mike; Gu, Jitty [Evans Analytical Group, 628 Hutton St., Raleigh, North Carolina 27606 (United States); Wagner, Brian P.; Jones, Evan B.; Howell, Robert S.; Nichols, Doyle T.; Young, Robert M. [Northrop Grumman Electronic Systems, Advanced Concepts and Technologies Division, 1212 Winterson Rd., Linthicum, Maryland 21090 (United States); Borodulin, Pavel [Northrop Grumman Electronic Systems, Advanced Concepts and Technologies Division, 1212 Winterson Rd., Linthicum, Maryland 21090 (United States); Department of Electrical and Computer Engineering, The Johns Hopkins University, Baltimore, Maryland 21218 (United States)

    2015-09-07

    Crystallization and amorphization phenomena in indirectly heated phase change material-based devices were investigated. Scanning transmission electron microscopy was utilized to explore GeTe phase transition processes in the context of the unique inline phase change switch (IPCS) architecture. A monolithically integrated thin film heating element successfully converted GeTe to ON and OFF states. Device cycling prompted the formation of an active area which sustains the majority of structural changes during pulsing. A transition region on both sides of the active area consisting of polycrystalline GeTe and small nuclei (<15 nm) in an amorphous matrix was also observed. The switching mechanism, determined by variations in pulsing parameters, was shown to be predominantly growth-driven. A preliminary model for crystallization and amorphization in IPCS devices is presented.

  4. Morphological analysis of GeTe in inline phase change switches

    International Nuclear Information System (INIS)

    King, Matthew R.; El-Hinnawy, Nabil; Salmon, Mike; Gu, Jitty; Wagner, Brian P.; Jones, Evan B.; Howell, Robert S.; Nichols, Doyle T.; Young, Robert M.; Borodulin, Pavel

    2015-01-01

    Crystallization and amorphization phenomena in indirectly heated phase change material-based devices were investigated. Scanning transmission electron microscopy was utilized to explore GeTe phase transition processes in the context of the unique inline phase change switch (IPCS) architecture. A monolithically integrated thin film heating element successfully converted GeTe to ON and OFF states. Device cycling prompted the formation of an active area which sustains the majority of structural changes during pulsing. A transition region on both sides of the active area consisting of polycrystalline GeTe and small nuclei (<15 nm) in an amorphous matrix was also observed. The switching mechanism, determined by variations in pulsing parameters, was shown to be predominantly growth-driven. A preliminary model for crystallization and amorphization in IPCS devices is presented

  5. Scaling linear colliders to 5 TeV and above

    International Nuclear Information System (INIS)

    Wilson, P.B.

    1997-04-01

    Detailed designs exist at present for linear colliders in the 0.5-1.0 TeV center-of-mass energy range. For linear colliders driven by discrete rf sources (klystrons), the rf operating frequencies range from 1.3 GHz to 14 GHz, and the unloaded accelerating gradients from 21 MV/m to 100 MV/m. Except for the collider design at 1.3 GHz (TESLA) which uses superconducting accelerating structures, the accelerating gradients vary roughly linearly with the rf frequency. This correlation between gradient and frequency follows from the necessity to keep the ac open-quotes wall plugclose quotes power within reasonable bounds. For linear colliders at energies of 5 TeV and above, even higher accelerating gradients and rf operating frequencies will be required if both the total machine length and ac power are to be kept within reasonable limits. An rf system for a 5 TeV collider operating at 34 GHz is outlined, and it is shown that there are reasonable candidates for microwave tube sources which, together with rf pulse compression, are capable of supplying the required rf power. Some possibilities for a 15 TeV collider at 91 GHz are briefly discussed

  6. Minimization of Dead-Periods in MRI Pulse Sequences for Imaging Oblique Planes

    Science.gov (United States)

    Atalar, Ergin; McVeigh, Elliot R.

    2007-01-01

    With the advent of breath-hold MR cardiac imaging techniques, the minimization of TR and TE for oblique planes has become a critical issue. The slew rates and maximum currents of gradient amplifiers limit the minimum possible TR and TE by adding dead-periods to the pulse sequences. We propose a method of designing gradient waveforms that will be applied to the amplifiers instead of the slice, readout, and phase encoding waveforms. Because this method ensures that the gradient amplifiers will always switch at their maximum slew rate, it results in the minimum possible dead-period for given imaging parameters and scan plane position. A GRASS pulse sequence has been designed and ultra-short TR and TE values have been obtained with standard gradient amplifiers and coils. For some oblique slices, we have achieved shorter TR and TE values than those for nonoblique slices. PMID:7869900

  7. Charge transport properties of CdMnTe radiation detectors

    Directory of Open Access Journals (Sweden)

    Prokopovich D. A.

    2012-10-01

    Full Text Available Growth, fabrication and characterization of indium-doped cadmium manganese telluride (CdMnTe radiation detectors have been described. Alpha-particle spectroscopy measurements and time resolved current transient measurements have yielded an average charge collection efficiency approaching 100 %. Spatially resolved charge collection efficiency maps have been produced for a range of detector bias voltages. Inhomogeneities in the charge transport of the CdMnTe crystals have been associated with chains of tellurium inclusions within the detector bulk. Further, it has been shown that the role of tellurium inclusions in degrading charge collection is reduced with increasing values of bias voltage. The electron drift velocity was calculated from the rise time distribution of the preamplifier output pulses at each measured bias. From the dependence of drift velocity on applied electric field the electron mobility was found to be μn = (718 ± 55 cm2/Vs at room temperature.

  8. Ultrafast optical manipulation of atomic motion in multilayer Ge-Sb-Te phase change materials

    Directory of Open Access Journals (Sweden)

    Fons P.

    2013-03-01

    Full Text Available Phase change random access memory devices have evolved dramatically with the recent development of superlattice structure of Ge-Sb-Te material (GST-SL in terms of its low power consumption. The phase change in GST-SL is mainly characterized by the displacement of Ge atoms. Here we examine a new phase change method, that is the manipulation of Ge-Te bonds using linearly-polarized femtosecond near-infrared optical pulses. As a result, we found that the p-polarized pump pulse is more effective in inducing the reversible and irreversible displacement of Ge atoms along [111] direction in the local structure. This structural change would be induced by the anisotropic carrier-phonon interaction along the [111] direction created by the p-polarized pulse.

  9. Schreibende Messgeräte

    Science.gov (United States)

    Plaßmann, Wilfried

    Die schreibenden Messgeräte werden hauptsächlich eingesetzt, um Vorgänge aufzuzeichnen und zu dokumentieren, die sich im Minuten- und Stunden-Bereich abspielen. Sie sind weitgehend durch Oszilloskope oder elektronische Geräte ähnlich einem Oszilloskop ersetzt worden, die entsprechend für Langzeitaufnahmen ausgelegt sind. Der Vorteil dieser Geräte gegenüber den schreibenden Messgeräten ist der, dass die Daten dauerhaft gespeichert sind, einschließlich der notwendigen Kenngrößen wie Zeitmaßstab, Amplitude, Datum, Aufzeichnungsgerät usw., und sich in dieser Form beliebig oft ausdrucken und vor allem direkt weiterverarbeiten lassen. Weiterhin entfallen die Probleme mit der Mechanik, dem Papier und den Schreibstiften. Deshalb folgt hier eine nur kurze Darstellung der Geräte.

  10. Numerical design and analysis of a compact TE10 to TE01 mode transducer

    International Nuclear Information System (INIS)

    Tantawi, S.; Ko, K.; Kroll, N.

    1993-04-01

    A high-power low-loss mode transducer design has been proposed to adapt the output of the X-Band klystron, WR90 rectangular waveguide, to the input of the pulse compression system, SLED II, which utilizes overmoded circular waveguides operating in the low-loss TE 01 mode. This device is much more compact than the conventional Marie type mode converters. The device splits the incoming klystron output into two separate rectangular guides that are then fed into a circular guide through a four-slot arrangement. We will use both MAFIA and HFSS to calculate the transmission properties of the three-dimensional structure. We will also determine the extent of mode contamination and compare the numerical results with experiments

  11. Few-cycle Optical Parametric Chirped Pulse Amplification

    Science.gov (United States)

    2007-01-08

    silicon - 150mm suprasi1300 Figure 10. Stretcher-compressor unit: group delay 5 -45mm TeO2 (ordinary) (GD) of 30mm silicon, 150mm suprasil300, 45mm CL 0...cycle pulse characterization: 840 -Measured raw 2DSI 20 °OA- traces for pulse (a) before 02. -and (b) after dispersion D 0 by glass plate; (c) so...fused silica plateJ19] see Fig. 15(a), along with the extracted spectral group delays. The chirp introduced by the glass plate is reflected in the

  12. Gamma transitions in 127Te

    International Nuclear Information System (INIS)

    Batista, Wagner Fonseca; Zamboni, Cibele Bugno

    2009-01-01

    This study of the 127 Te β - decay was carried out by means of gamma spectroscopy measurements using high resolution Ge detector, in the region from 150 keV up to 1000 keV, aiming to get a better understanding of the 127 Te nuclear structure. Several gamma transitions were confirmed when compared with those published in the last compilation. These data resulting in lower uncertainty. (author)

  13. The 'Harmonizing Optimal Strategy for Treatment of coronary artery stenosis - sAfety & effectiveneSS of drug-elUting stents & antiplatelet REgimen' (HOST-ASSURE trial: study protocol for a randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Park Kyung

    2012-03-01

    Full Text Available Abstract Background Second-generation drug-eluting stents (DES have raised the bar of clinical performance. These stents are mostly made from cobalt chromium alloy. A newer generation DES has been developed from platinum chromium alloy, but clinical data regarding the efficacy and safety of the platinum chromium-based everolimus-eluting stent (PtCr-EES is limited, with no comparison data against the cobalt chromium-based zotarolimus-eluting stent (CoCr-ZES. In addition, an antiplatelet regimen is an integral component of medical therapy after percutaneous coronary intervention (PCI. A 1-week duration of doubling the dose of clopidogrel (double-dose antiplatelet therapy (DDAT was shown to improve outcome at 1 month compared with conventional dose in acute coronary syndrome (ACS patients undergoing PCI. However in Asia, including Korea, the addition of cilostazol (triplet antiplatelet therapy (TAT is used more commonly than doubling the dose of clopidogrel in high-risk patients. Methods In the 'Harmonizing Optimal Strategy for Treatment of coronary artery stenosis - sAfety & effectiveneSS of drug-elUting stents & antiplatelet REgimen' (HOST-ASSURE trial, approximately 3,750 patients are being prospectively and randomly assigned in a 2 × 2 factorial design according to the type of stent (PtCr-EES vs CoCr-ZES and antiplatelet regimen (TAT vs DDAT. The first primary endpoint is target lesion failure at 1 year for the stent comparison, and the second primary endpoint is net clinical outcome at 1 month for comparison of antiplatelet therapy regimen. Discussion The HOST-ASSURE trial is the largest study yet performed to directly compare the efficacy and safety of the PtCr-EES versus CoCr-ZES in an 'all-comers' population. In addition, this study will also compare the clinical outcome of TAT versus DDAT for 1-month post PCI. Trial registration ClincalTrials.gov number NCT01267734.

  14. Study of the fast inversion recovery pulse sequence. With reference to fast fluid attenuated inversion recovery and fast short TI inversion recovery pulse sequence

    International Nuclear Information System (INIS)

    Tsuchihashi, Toshio; Maki, Toshio; Suzuki, Takeshi

    1997-01-01

    The fast inversion recovery (fast IR) pulse sequence was evaluated. We compared the fast fluid attenuated inversion recovery (fast FLAIR) pulse sequence in which inversion time (TI) was established as equal to the water null point for the purpose of the water-suppressed T 2 -weighted image, with the fast short TI inversion recovery (fast STIR) pulse sequence in which TI was established as equal to the fat null point for purpose of fat suppression. In the fast FLAIR pulse sequence, the water null point was increased by making TR longer. In the FLAIR pulse sequence, the longitudinal magnetization contrast is determined by TI. If TI is increased, T 2 -weighted contrast improves in the same way as increasing TR for the SE pulse sequence. Therefore, images should be taken with long TR and long TI, which are longer than TR and longer than the water null point. On the other hand, the fat null point is not affected by TR in the fast STIR pulse sequence. However, effective TE was affected by variation of the null point. This increased in proportion to the increase in effective TE. Our evaluation indicated that the fast STIR pulse sequence can control the extensive signals from fat in a short time. (author)

  15. Ultrashort Laser Pulse Phenomena

    CERN Document Server

    Diels, Jean-Claude

    2006-01-01

    Ultrashort Laser Pulse Phenomena, 2e serves as an introduction to the phenomena of ultra short laser pulses and describes how this technology can be used to examine problems in areas such as electromagnetism, optics, and quantum mechanics. Ultrashort Laser Pulse Phenomena combines theoretical backgrounds and experimental techniques and will serve as a manual on designing and constructing femtosecond (""faster than electronics"") systems or experiments from scratch. Beyond the simple optical system, the various sources of ultrashort pulses are presented, again with emphasis on the basic

  16. Switching of localized surface plasmon resonance of gold nanoparticles on a GeSbTe film mediated by nanoscale phase change and modification of surface morphology

    Energy Technology Data Exchange (ETDEWEB)

    Hira, T.; Homma, T.; Uchiyama, T.; Kuwamura, K.; Saiki, T. [Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama, Kanagawa 223-8522 (Japan)

    2013-12-09

    As a platform for active nanophotonics, localized surface plasmon resonance (LSPR) switching via interaction with a chalcogenide phase change material (GeSbTe) was investigated. We performed single-particle spectroscopy of gold nanoparticles placed on a GeSbTe thin film. By irradiation with a femtosecond pulsed laser for amorphization and a continuous wave laser for crystallization, significant switching behavior of the LSPR band due to the interaction of GeSbTe was observed. The switching mechanism was explained in terms of both a change in the refractive index and a modification of surface morphology accompanying volume expansion and reduction of GeSbTe.

  17. Extended defects in MBE-grown CdTe-based solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wichrowska, Karolina; Wosinski, Tadeusz; Kret, Slawomir; Chusnutdinow, Sergij; Karczewski, Grzegorz [Institute of Physics, Polish Academy of Sciences, Warsaw (Poland); Rawski, Michal [Analytical Laboratory, Maria Curie-Sklodowska University, Lublin (Poland); Yastrubchak, Oksana [Institute of Physics, Maria Curie-Sklodowska University, Lublin (Poland)

    2015-08-15

    Extended defects in the p -ZnTe/n -CdTe heterojunctions grown by the molecular-beam epitaxy technique on two different substrates, GaAs and CdTe, have been investigated by deep-level transient spectroscopy (DLTS) and transmission electron microscopy (TEM). Four hole traps, called H1 to H4, and one electron trap, called E3, have been revealed in the DLTS spectra measured for the heterojunctions grown on the GaAs substrates. The H1, H3, H4 and E3 traps have been attributed to the electronic states of dislocations on the ground of their logarithmic capture kinetics. The DLTS peaks associated with the H1 and E3 traps were not observed in the DLTS spectra measured for the heterojunction grown on the CdTe substrate. They are most likely associated with threading dislocations generated at the mismatched interface with the GaAs substrate. Cross-sectional TEM images point out that they are dislocations of the 60 -type. In both the types of heterojunctions the H4 trap was observed only under forward-bias filling pulse, suggesting that this trap is associated with the CdTe/ZnTe interface. In addition, TEM images revealed also the presence of intrinsic and extrinsic stacking faults in the CdTe layers, which may considerably affect their electronic properties. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Laser ablation in CdZnTe crystal due to thermal self-focusing: Secondary phase hydrodynamic expansion

    Energy Technology Data Exchange (ETDEWEB)

    Medvid’, A., E-mail: mychko@latnet.lv [Riga Technical University, 3 Paula Valdena Str., LV-1048 Riga (Latvia); Mychko, A.; Dauksta, E. [Riga Technical University, 3 Paula Valdena Str., LV-1048 Riga (Latvia); Kosyak, V. [Sumy State University, 2, Rymskogo-Korsakova St., 40007 Sumy (Ukraine); Grase, L. [Riga Technical University, 3 Paula Valdena Str., LV-1048 Riga (Latvia)

    2016-06-30

    Highlights: • We found two laser induced threshold intensity for CdZnTe crystal. • The laser beam self-focusing lead to increase of intensity of laser radiation at exit surface. • Laser ablation is a result of Te inclusion hydrodynamic expansion. - Abstract: The present paper deals with the laser ablation in CdZnTe crystal irradiated by pulsed infrared laser. Two values of threshold intensities of the laser ablation were determined, namely of about 8.5 and 6.2 MW/cm{sup 2} for the incident and the rear surfaces, correspondingly. Lower intensity of the laser ablation for the rear surface is explained by thermal self-focusing of the laser beam in the CdZnTe crystal due to heating of Te inclusions with a following hydrodynamic expansion.

  19. Diagnóstico para promover un plan de calidad para la Universidad Tecnológica Equinoccial: Caso E2662 Docentes de Educación a distancia de la carrera de Ingeniería en Administración de Empresas de Servicios y Recursos Humanos de la Universidad Tecnológica Equinoccial (UTE)

    OpenAIRE

    Acosta Briones, César Patricio

    2009-01-01

    75 hojas : ilustraciones, ilustraciones, + CD-ROM 2370 La investigación a nivel de diagnóstico versa sobre la situación de los docentes de Educación a Distancia de la Carrera de Ingeniería en Administración de Servicios y Recursos Humanos. Este trabajo se ha desarrollado en cuatro capítulos que tienen el siguiente contenido. El primero, un señalamiento de una breve historia, de la calidad en la época moderna y principales exponentes y modelos de calidad, que podría tomar la UTE, para ...

  20. Optical phonons in PbTe/CdTe multilayer heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Novikova, N. N.; Yakovlev, V. A. [Russian Academy of Sciences, Institute for Spectroscopy (Russian Federation); Kucherenko, I. V., E-mail: kucheren@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Karczewski, G. [Polish Academy of Sciences, Institute of Physics (Poland); Aleshchenko, Yu. A.; Muratov, A. V.; Zavaritskaya, T. N.; Melnik, N. N. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2015-05-15

    The infrared reflection spectra of PbTe/CdTe multilayer nanostructures grown by molecular-beam epitaxy are measured in the frequency range of 20–5000 cm{sup −1} at room temperature. The thicknesses and high-frequency dielectric constants of the PbTe and CdTe layers and the frequencies of the transverse optical (TO) phonons in these structures are determined from dispersion analysis of the spectra. It is found that the samples under study are characterized by two TO phonon frequencies, equal to 28 and 47 cm{sup −1}. The first frequency is close to that of TO phonons in bulk PbTe, and the second is assigned to the optical mode in structurally distorted interface layers. The Raman-scattering spectra upon excitation with the radiation of an Ar{sup +} laser at 514.5 nm are measured at room and liquid-nitrogen temperatures. The weak line at 106 cm{sup −1} observed in these spectra is attributed to longitudinal optical phonons in the interface layers.

  1. Characterisation of Redlen high-flux CdZnTe

    Science.gov (United States)

    Thomas, B.; Veale, M. C.; Wilson, M. D.; Seller, P.; Schneider, A.; Iniewski, K.

    2017-12-01

    CdZnTe is a promising material for the current generation of free electron laser light sources and future laser-driven γ-ray sources which require detectors capable of high flux imaging at X-ray and γ-ray energies (> 10 keV) . However, at high fluxes CdZnTe has been shown to polarise due to hole trapping, leading to poor performance. Novel Redlen CdZnTe material with improved hole transport properties has been designed for high flux applications. Small pixel CdZnTe detectors were fabricated by Redlen Technologies and flip-chip bonded to PIXIE ASICs. An XIA Digital Gamma Finder PIXIE-16 system was used to digitise each of the nine analogue signals with a timing resolution of 10 ns. Pulse shape analysis was used to extract the rise times and amplitude of signals. These were measured as a function of applied bias voltage and used to calculate the mobility (μ) and mobility-lifetime (μτ) of electrons and holes in the material for three identical detectors. The measured values of the transport properties of electrons in the high-flux-capable material was lower than previously reported for Redlen CdZnTe material (μeτe ~ 1 × 10-3 cm2V-1 and μe ~ 1000 cm2V-1s-1) while the hole transport properties were found to have improved (μhτh ~ 3 × 10-4 cm2V-1 and μh ~ 100 cm2V-1s-1).

  2. Gas phase pulse radiolysis

    International Nuclear Information System (INIS)

    Jonah, C.D.; Andong Liu; Mulac, W.A.

    1987-01-01

    Gas phase pulse radiolysis, a technique which can be used to study many different phenomena in chemistry and physics, is discussed. As a source of small radicals, pulse radiolysis is important to the field of chemistry, particularly to combustion and atmospheric kinetics. The reactions of 1,3-butadiene, allene, ethylene and acetylene with OH are presented. 52 refs., 1 fig., 1 tab

  3. Pulse duration discriminator

    International Nuclear Information System (INIS)

    Kosakovskij, L.F.

    1980-01-01

    Basic circuits of a discriminator for discrimination of pulses with the duration greater than the preset one, and of a multifunctional discriminator allowing to discriminate pulses with the duration greater (tsub(p)>tsub(s)) and lesser (tsub(p) tsub(s) and with the duration tsub(p) [ru

  4. Sources of pulsed radiation

    International Nuclear Information System (INIS)

    Sauer, M.C. Jr.

    1981-01-01

    Characteristics of various sources of pulsed radiation are examined from the viewpoint of their importance to the radiation chemist, and some examples of uses of such sources are mentioned. A summary is given of the application of methods of physical dosimetry to pulsed sources, and the calibration of convenient chemical dosimeters by physical dosimetry is outlined. 7 figures, 1 table

  5. Pulsed neutron generator

    International Nuclear Information System (INIS)

    Bespalov, D.F.; Bykovskii, Yu.A.; Vergun, I.I.; Kozlovskii, K.I.; Kozyrev, Yu.P.; Leonov, R.K.; Simagin, B.I.; Tsybin, A.S.; Shikanov, A.Ie.

    1986-03-01

    The paper describes a new device for generating pulsed neutron fields, utilized in nuclear geophysics for carrying out pulsed neutron logging and activation analysis under field conditions. The invention employs a sealed-off neutron tube with a laser ion source which increases neutron yield to the level of 10 neutrons per second or higher. 2 refs., 1 fig

  6. Bipolar pulse generator for intense pulsed ion beam accelerator

    International Nuclear Information System (INIS)

    Ito, H.; Igawa, K.; Kitamura, I.; Masugata, K.

    2007-01-01

    A new type of pulsed ion beam accelerator named ''bipolar pulse accelerator'' (BPA) has been proposed in order to improve the purity of intense pulsed ion beams. To confirm the principle of the BPA, we developed a bipolar pulse generator for the bipolar pulse experiment, which consists of a Marx generator and a pulse forming line (PFL) with a rail gap switch on its end. In this article, we report the first experimental result of the bipolar pulse and evaluate the electrical characteristics of the bipolar pulse generator. When the bipolar pulse generator was operated at 70% of the full charge condition of the PFL, the bipolar pulse with the first (-138 kV, 72 ns) and the second pulse (+130 kV, 70 ns) was successfully obtained. The evaluation of the electrical characteristics indicates that the developed generator can produce the bipolar pulse with fast rise time and sharp reversing time

  7. Pulse induction heating

    Energy Technology Data Exchange (ETDEWEB)

    Vasiliev, A S; Kachanov, B Y; Kogan, B V

    1993-12-31

    Induction heating and three types of pulse processes were studied. It was found that in pulse processes the frequency and pulse duration of heat treatments do not remain constant. High frequency pulse heat treatments can be used on sprayed coatings; such treatments will result in stronger surfaces with no cracks. For induction hardening, the rate of specific power was 1 to 1.5 kW/sq.cm, for forging it was 0.2 to 0.3 kW/sq.cm and for melting it was 0.05 to 0.1 kW/sq.cm. The application of pulse heating will result in higher rates of specific power.

  8. Superstrengthening Bi2Te3 through Nanotwinning

    Science.gov (United States)

    Li, Guodong; Aydemir, Umut; Morozov, Sergey I.; Wood, Max; An, Qi; Zhai, Pengcheng; Zhang, Qingjie; Goddard, William A.; Snyder, G. Jeffrey

    2017-08-01

    Bismuth telluride (Bi2Te3 ) based thermoelectric (TE) materials have been commercialized successfully as solid-state power generators, but their low mechanical strength suggests that these materials may not be reliable for long-term use in TE devices. Here we use density functional theory to show that the ideal shear strength of Bi2Te3 can be significantly enhanced up to 215% by imposing nanoscale twins. We reveal that the origin of the low strength in single crystalline Bi2Te3 is the weak van der Waals interaction between the Te1 coupling two Te 1 - Bi - Te 2 - Bi - Te 1 five-layer quint substructures. However, we demonstrate here a surprising result that forming twin boundaries between the Te1 atoms of adjacent quints greatly strengthens the interaction between them, leading to a tripling of the ideal shear strength in nanotwinned Bi2Te3 (0.6 GPa) compared to that in the single crystalline material (0.19 GPa). This grain boundary engineering strategy opens a new pathway for designing robust Bi2Te3 TE semiconductors for high-performance TE devices.

  9. Pulse Distortion in Saturated Fiber Optical Parametric Chirped Pulse Amplification

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Da Ros, Francesco; Rottwitt, Karsten

    2012-01-01

    Fiber optical parametric chirped pulse amplification is experimentally compared for different chirped pulses in the picosecond regime. The amplified chirped pulses show distortion appearing as pedestals after recompression when the amplifier is operated in saturation.......Fiber optical parametric chirped pulse amplification is experimentally compared for different chirped pulses in the picosecond regime. The amplified chirped pulses show distortion appearing as pedestals after recompression when the amplifier is operated in saturation....

  10. Optical pulse compression

    International Nuclear Information System (INIS)

    Glass, A.J.

    1975-01-01

    The interest in using large lasers to achieve a very short and intense pulse for generating fusion plasma has provided a strong impetus to reexamine the possibilities of optical pulse compression at high energy. Pulse compression allows one to generate pulses of long duration (minimizing damage problems) and subsequently compress optical pulses to achieve the short pulse duration required for specific applications. The ideal device for carrying out this program has not been developed. Of the two approaches considered, the Gires--Tournois approach is limited by the fact that the bandwidth and compression are intimately related, so that the group delay dispersion times the square of the bandwidth is about unity for all simple Gires--Tournois interferometers. The Treacy grating pair does not suffer from this limitation, but is inefficient because diffraction generally occurs in several orders and is limited by the problem of optical damage to the grating surfaces themselves. Nonlinear and parametric processes were explored. Some pulse compression was achieved by these techniques; however, they are generally difficult to control and are not very efficient. (U.S.)

  11. Comprehensive thermodynamic description of the quasiternary system PbTe-GeTe-SnTe

    International Nuclear Information System (INIS)

    Yashina, Lada V.; Leute, Volkmar; Shtanov, Vladimir I.; Schmidtke, Heinrich M.; Neudachina, Vera S.

    2006-01-01

    The equilibrium phase diagram of the quasiternary system PbTe-GeTe-SnTe was studied experimentally in the ranges of spinodal demixing and (solid + liquid) equilibrium by means of X-ray diffraction (XRD), electron microprobe analysis (EMA) and differential thermal analysis (DTA). A model description of the phase diagram was done on the base of composition dependent interaction parameters, which were determined for the solid and the liquid phases. The interaction parameters for the quasibinary systems were recalculated in order to reach better correlation between all experimental data. It was shown that the quasiternary phase diagram can be principally described using the interaction parameters for the quasibinary subsystems, but an additional ternary interaction parameter has also to be considered. The local structure of the quasiternary solid solution is described by a four-particle cluster model. Due to the tendency of the solid solution to demix, the probability of the (GeGeGe)Te cluster was found to be higher and that of the (PbGeGe)Te cluster to be lower than it is expected for the purely statistical distribution of the clusters

  12. M rate at TE. Monitoring at TeV energies

    Energy Technology Data Exchange (ETDEWEB)

    Dorner, Daniela [Universitaet Wuerzburg (Germany); Bretz, Thomas [RWTH Aachen (Germany); Gonzalez, Magdalena; Alfaro, Ruben [Universidad Nacional Autonoma de Mexico (Mexico); Tovmassian, Gagik [Instituto de Astronomia Sede Ensenada (Mexico)

    2016-07-01

    A dedicated long-term monitoring programm at TeV energies has been started by the FACT project about four years ago. Being limited to one site, gaps due to the rotation of the Earth remain in the measured light curves. This makes it difficult to study typical variability time scales of few hours to one day. To allow for systematic studies of continuous observations over up to 12 hours, a second telescope is being installed at a site in about six hours distance in longitude. For the M rate at TE (Monitoring at TeV energies) telescope, a mount from a previous experiment is being refurbished and will be equipped with a new camera. Using silicon based photo sensors like in FACT, an excellent and stable performance will be achieved. M rate at TE is a joint project of German and Mexican universities which aims at extending the blazar monitoring to so far unexplored time ranges. In the presentation, the status of this emerging project is reported.

  13. Femtosecond response time measurements of a Cs2Te photocathode

    Science.gov (United States)

    Aryshev, A.; Shevelev, M.; Honda, Y.; Terunuma, N.; Urakawa, J.

    2017-07-01

    Success in design and construction of a compact, high-brightness accelerator system is strongly related to the production of ultra-short electron beams. Recently, the approach to generate short electron bunches or pre-bunched beams in RF guns directly illuminating a high quantum efficiency semiconductor photocathode with femtosecond laser pulses has become attractive. The measurements of the photocathode response time in this case are essential. With an approach of the interferometer-type pulse splitter deep integration into a commercial Ti:Sa laser system used for RF guns, it has become possible to generate pre-bunched electron beams and obtain continuously variable electron bunch separation. In combination with a well-known zero-phasing technique, it allows us to estimate the response time of the most commonly used Cs2Te photocathode. It was demonstrated that the peak-to-peak rms time response of Cs2Te is of the order of 370 fs, and thereby, it is possible to generate and control a THz sequence of relativistic electron bunches by a conventional S-band RF gun. This result can also be applied for investigation of other cathode materials and electron beam temporal shaping and further opens a possibility to construct wide-range tunable, table-top THz free electron laser.

  14. Dynamic pulse difference circuit

    International Nuclear Information System (INIS)

    Erickson, G.L.

    1978-01-01

    A digital electronic circuit of especial use for subtracting background activity pulses in gamma spectrometry is disclosed which comprises an up-down counter connected to count up with signal-channel pulses and to count down with background-channel pulses. A detector responsive to the count position of the up-down counter provides a signal when the up-down counter has completed one scaling sequence cycle of counts in the up direction. In an alternate embodiment, a detector responsive to the count position of the up-down counter provides a signal upon overflow of the counter

  15. Coaxial pulse matching transformer

    International Nuclear Information System (INIS)

    Ledenev, V.V.; Khimenko, L.T.

    1986-01-01

    This paper describes a coaxial pulse matching transformer with comparatively simple design, increased mechanical strength, and low stray inductance. The transformer design makes it easy to change the turns ratio. The circuit of the device and an expression for the current multiplication factor are presented; experiments confirm the efficiency of the transformer. Apparatus with a coaxial transformer for producing high-power pulsed magnetic fields is designed (current pulses of 1-10 MA into a load and a natural frequency of 100 kHz)

  16. Pulse-width discriminators

    International Nuclear Information System (INIS)

    Budyashov, Yu.G.; Grebenyuk, V.M.; Zinov, V.G.

    1978-01-01

    A pulse duration discriminator is described which is intended for processing signals from multilayer scintillators. The basic elements of the scintillator are: an input gate, a current generator, an integrating capacitor, a Schmidt trigger and an anticoincidence circuit. The basic circuit of the discriminator and its time diagrams explaining its operating are given. The discriminator is based on microcircuits. Pulse duration discrimination threshold changes continuously from 20 to 100 ns, while its amplitude threshold changes within 20 to 100 mV. The temperature instability of discrimination thresholds (both in pulse width and in amplitude) is better than 0.1 per cent/deg C

  17. Multimode pulse counter

    International Nuclear Information System (INIS)

    Natanzon, D.D.

    1982-01-01

    A pulse counter with code conversion is described. The counter is based on the integrated circuits of direct-counting devices of medium integration. The counter ensures various modes of pulse counting depending on the logical control signals: reversible, two-channel summing, one-channel summing binary, summing with ''storage'' signal code fixation without interrupting pulse counting. Arrangement of the suggested structure as a microcircuit of medium integration might contribute to reduction in the counter type nomenclature in digital families of widely used integrated circuits

  18. Pulsed atomic soliton laser

    International Nuclear Information System (INIS)

    Carr, L.D.; Brand, J.

    2004-01-01

    It is shown that simultaneously changing the scattering length of an elongated, harmonically trapped Bose-Einstein condensate from positive to negative and inverting the axial portion of the trap, so that it becomes expulsive, results in a train of self-coherent solitonic pulses. Each pulse is itself a nondispersive attractive Bose-Einstein condensate that rapidly self-cools. The axial trap functions as a waveguide. The solitons can be made robustly stable with the right choice of trap geometry, number of atoms, and interaction strength. Theoretical and numerical evidence suggests that such a pulsed atomic soliton laser can be made in present experiments

  19. DogPulse

    DEFF Research Database (Denmark)

    Skovgaard, Christoffer; Thomsen, Josephine Raun; Verdezoto, Nervo

    2015-01-01

    This paper presents DogPulse, an ambient awareness system to support the coordination of dog walking among family members at home. DogPulse augments a dog collar and leash set to activate an ambient shape-changing lamp and visualize the last time the dog was taken for a walk. The lamp gradually...... changes its form and pulsates its lights in order to keep the family members aware of the dog walking activity. We report the iterative prototyping of DogPulse, its implementation and its preliminary evaluation. Based on our initial findings, we present the limitations and lessons learned as well...

  20. WE-AB-204-06: Pseudo-CT Generation Using Undersampled, Single-Acquisition UTE-MDixon and Direct-Mapping Artificial Neural Networks for MR-Based Attenuation Correction and Radiation Therapy Planning

    Energy Technology Data Exchange (ETDEWEB)

    Su, K; Kuo, J [Case Center for Imaging Research, Case Western Reserve University, Cleveland, Ohio (United States); Department of Radiology, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio (United States); Hu, L; Traughber, M [Philips Healthcare, Cleveland, Ohio (United States); Pereira, G; Traughber, B [Department of Radiation Oncology, University Hospitals Seidman Cancer Center, Case Western Reserve University, Cleveland, Ohio (United States); Herrmann, K [Department of Radiology, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio (United States); Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio (United States); Muzic, R [Case Center for Imaging Research, Case Western Reserve University, Cleveland, Ohio (United States); Department of Radiology, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio (United States); Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH (United States)

    2015-06-15

    Purpose: Emerging technologies such as dedicated PET/MRI and MR-therapy systems require robust and clinically practical methods for determining photon attenuation. Herein, we propose using novel MR acquisition methods and processing for the generation of pseudo-CTs. Methods: A single acquisition, 190-second UTE-mDixon sequence with 25% (angular) sampling density and 3D radial readout was performed on nine volunteers. Three water-filled tubes were placed in the FOV for trajectory-delay correction. The MR data were reconstructed to generate three primitive images acquired at TEs of 0.1, 1.5 and 2.8 ms. In addition, three derived MR images were generated, i.e. two-point Dixon water/fat separation and R2* (1/T2*) map. Furthermore, two spatial features, i.e. local binary pattern (S-1) and relative spatial coordinates (S-2), were incorporated. A direct-mapping operator was generated using Artificial Neural Networks (ANNs) for transforming the MR features to a pseudo-CT. CT images served as the training data and, using a leave-one-out method, for performance evaluation using mean prediction deviation (MPD), mean absolute prediction deviation (MAPD), and correlation coefficient (R). Results: The errors between measured CT and pseudo-CT declined dramatically when the spatial features, i.e. S-1 and S-2, were included. The MPD, MAPD, and R were, respectively, 5±57 HU, 141±41 HU, and 0.815±0.066 for results generated by the ANN trained without the spatial features and were 32±26 HU, 115±18 HU, and 0.869±0.035 with the spatial features. The estimation errors of the pseudo-CT were smaller when both the S-1 and S-2 were used together than when either the S-1 or the S-2 was used. Pseudo-CT generation (256×256×256 voxels) by ANN took < 0.5 s using a computer having an Intel i7 3.4GHz CPU and 16 GB RAM. Conclusion: The proposed direct-mapping ANN approach is a technically accurate, clinically practical method for pseudo-CT generation and can potentially help improve the

  1. WE-AB-204-06: Pseudo-CT Generation Using Undersampled, Single-Acquisition UTE-MDixon and Direct-Mapping Artificial Neural Networks for MR-Based Attenuation Correction and Radiation Therapy Planning

    International Nuclear Information System (INIS)

    Su, K; Kuo, J; Hu, L; Traughber, M; Pereira, G; Traughber, B; Herrmann, K; Muzic, R

    2015-01-01

    Purpose: Emerging technologies such as dedicated PET/MRI and MR-therapy systems require robust and clinically practical methods for determining photon attenuation. Herein, we propose using novel MR acquisition methods and processing for the generation of pseudo-CTs. Methods: A single acquisition, 190-second UTE-mDixon sequence with 25% (angular) sampling density and 3D radial readout was performed on nine volunteers. Three water-filled tubes were placed in the FOV for trajectory-delay correction. The MR data were reconstructed to generate three primitive images acquired at TEs of 0.1, 1.5 and 2.8 ms. In addition, three derived MR images were generated, i.e. two-point Dixon water/fat separation and R2* (1/T2*) map. Furthermore, two spatial features, i.e. local binary pattern (S-1) and relative spatial coordinates (S-2), were incorporated. A direct-mapping operator was generated using Artificial Neural Networks (ANNs) for transforming the MR features to a pseudo-CT. CT images served as the training data and, using a leave-one-out method, for performance evaluation using mean prediction deviation (MPD), mean absolute prediction deviation (MAPD), and correlation coefficient (R). Results: The errors between measured CT and pseudo-CT declined dramatically when the spatial features, i.e. S-1 and S-2, were included. The MPD, MAPD, and R were, respectively, 5±57 HU, 141±41 HU, and 0.815±0.066 for results generated by the ANN trained without the spatial features and were 32±26 HU, 115±18 HU, and 0.869±0.035 with the spatial features. The estimation errors of the pseudo-CT were smaller when both the S-1 and S-2 were used together than when either the S-1 or the S-2 was used. Pseudo-CT generation (256×256×256 voxels) by ANN took < 0.5 s using a computer having an Intel i7 3.4GHz CPU and 16 GB RAM. Conclusion: The proposed direct-mapping ANN approach is a technically accurate, clinically practical method for pseudo-CT generation and can potentially help improve the

  2. Fast Neutron Detection Using Pixelated CdZnTe Spectrometers

    Science.gov (United States)

    Streicher, Michael; Goodman, David; Zhu, Yuefeng; Brown, Steven; Kiff, Scott; He, Zhong

    2017-07-01

    Fast neutrons are an important signature of special nuclear materials (SNMs). They have a low natural background rate and readily penetrate high atomic number materials that easily shield gamma-ray signatures. Therefore, they provide a complementary signal to gamma rays for detecting shielded SNM. Scattering kinematics dictate that a large nucleus (such as Cd or Te) will recoil with small kinetic energy after an elastic collision with a fast neutron. Charge carrier recombination and quenching further reduce the recorded energy deposited. Thus, the energy threshold of CdZnTe detectors must be very low in order to sense the small signals from these recoils. In this paper, the threshold was reduced to less than 5 keVee to demonstrate that the 5.9-keV X-ray line from 55Fe could be separated from electronic noise. Elastic scattering neutron interactions were observed as small energy depositions (less than 20 keVee) using digitally sampled pulse waveforms from pixelated CdZnTe detectors. Characteristic gamma-ray lines from inelastic neutron scattering were also observed.

  3. Rapid thermal pulse annealing

    International Nuclear Information System (INIS)

    Miller, M.G.; Koehn, B.W.; Chaplin, R.L.

    1976-01-01

    Characteristics of recovery processes have been investigated for cases of heating a sample to successively higher temperatures by means of isochronal annealing or by using a rapid pulse annealing. A recovery spectra shows the same features independent of which annealing procedure is used. In order to determine which technique provides the best resolution, a study was made of how two independent first-order processes are separated for different heating rates and time increments of the annealing pulses. It is shown that the pulse anneal method offers definite advantages over isochronal annealing when annealing for short time increments. Experimental data by means of the pulse anneal techniques are given for the various substages of stage I of aluminium. (author)

  4. Pulse holographic measurement techniques

    International Nuclear Information System (INIS)

    Kim, Cheol Jung; Baik, Seong Hoon; Hong, Seok Kyung; Kim, Jeong Moog; Kim, Duk Hyun

    1992-01-01

    With the development of laser, remote inspection techniques using laser have been growing on. The inspection and measurement techniques by pulse holography are well-established technique for precise measurement, and widely used in various fields of industry now. In nuclear industry, this technology is practically used because holographic inspection is remote, noncontact, and precise measurement technique. In relation to remote inspection technology in nuclear industry, state-of-the art of pulse HNDT (Holographic non-destructive testing) and holographic measurement techniques are examined. First of all, the fundamental principles as well as practical problems for applications are briefly described. The fields of pulse holography have been divided into the HNDT, flow visualization and distribution study, and other application techniques. Additionally holographic particle study, bubble chamber holography, and applications to other visualization techniques are described. Lastly, the current status for the researches and applications of pulse holography to nuclear industry which are carried out actively in Europe and USA, is described. (Author)

  5. IAE pulsed electrostatic accelerator

    International Nuclear Information System (INIS)

    Afanas'ev, V.P.; Ganzhelyuk, M.L.; Kozlov, L.D.; Koltypin, E.A.; Molchanov, Yu.D.; Otroshchenko, G.A.; Yan'kov, G.B.

    1976-01-01

    The modernized pulse electrostatic accelerator using the klystron ion grouping and the beam interruption system prior to acceleration is described. The accelerator is modernized in order to improve parameters of a current pulse and to decrease the background in the measurement room. The ion beam of needed dimensions is obtained with the help of a high-frequency source and a beam grouping and deflection system. The general view of the beam grouping and deflection system is shown. The ion beam forming process is considered in detail. The modernized electrostatic accelerator permits to obtain a pulse current with a pulse length of 1.5 ns and an amplitude of 1.5 - 2 μA. With the repetition frequency of 2 MHz, the average target current is about 6 μA

  6. Crystallization behavior of Ge-doped eutectic Sb70Te30 films in optical disks

    International Nuclear Information System (INIS)

    Khulbe, Pramod K.; Hurst, Terril; Mansuripur, Masud; Horie, Michikazu

    2002-01-01

    We report laser-induced crystallization behavior of binary Sb-Te and ternary Ge-doped eutectic Sb70Te30 thin film samples in a typical quadrilayer stack as used in phase-change optical disk data storage. Several experiments have been conducted on a two-laser static tester in which one laser operating in pulse mode writes crystalline marks on amorphous film or amorphous marks on crystalline film, while the second laser operating at low-power cw mode simultaneously monitors the progress of the crystalline or amorphous mark formation in real time in terms of the reflectivity variation. The results of this study show that the crystallization kinetics of this class of film is strongly growth dominant, which is significantly different from the crystallization kinetics of stochiometric Ge-Sb-Te compositions. In Sb-Te and Ge-doped eutectic Sb70Te30 thin-film samples, the crystallization behavior of the two forms of amorphous states, namely, as-deposited amorphous state and melt-quenched amorphous state, remains approximately same. We have also presented experiments showing the effect of the variation of the Sb/Te ratio and Ge doping on the crystallization behavior of these films

  7. International Year of Pulses 2016 | 2016 International Year of Pulses

    Science.gov (United States)

    the Year in collaboration with Governments, relevant organizations, non-governmental organizations and the composition of pulses Image 4 Wrapping up the International Year of Pulses The 5 key messages to food security Infographic Pulses and climate change International Year of Pulses 2016 The 68th UN

  8. Realtime aspects of pulse-to-pulse modulation

    International Nuclear Information System (INIS)

    Steiner, R.; Riedel, C.; Roesch, W.

    1992-01-01

    The pulse-to-pulse modulation of the SIS-ESR control system is described. Fast response to operator interaction and to changes in process conditions is emphasized as well as the essential part played by the timing system in pulse-to-pulse modulation. (author)

  9. Te hard van stapel gelopen.

    NARCIS (Netherlands)

    W-J. Verhoeven (Willem-Jan)

    2008-01-01

    textabstractHoe goed we ook trachten de samenleving te organiseren, fraude maakt er deel van uit. Dit blijkt uit spraakmakende grote schandalen zoals de Enron-zaak, de Bouwfraude-zaak en de Nigerian letter scams. Maar fraude komt ook op minder geruchtmakende schaal voor, zoals oplichting op

  10. X = S, Se, Te) heterostructures

    KAUST Repository

    Zhang, Qingyun; Schwingenschlö gl, Udo

    2018-01-01

    Using first-principles calculations, we investigate the electronic properties of the two-dimensional GaX/MX2 (M = Mo, W; X = S, Se, Te) heterostructures. Orbital hybridization between GaX and MX2 is found to result in Rashba splitting at the valence

  11. Pulsed spallation Neutron Sources

    International Nuclear Information System (INIS)

    Carpenter, J.M.

    1994-01-01

    This paper reviews the early history of pulsed spallation neutron source development at Argonne and provides an overview of existing sources world wide. A number of proposals for machines more powerful than currently exist are under development, which are briefly described. The author reviews the status of the Intense Pulsed Neutron Source, its instrumentation, and its user program, and provides a few examples of applications in fundamental condensed matter physics, materials science and technology

  12. Pulsed spallation neutron sources

    International Nuclear Information System (INIS)

    Carpenter, J.M.

    1996-01-01

    This paper reviews the early history of pulsed spallation neutron source development ar Argonne and provides an overview of existing sources world wide. A number of proposals for machines more powerful than currently exist are under development, which are briefly described. The author reviews the status of the Intense Pulsed Neutron Source, its instrumentation, and its user program, and provide a few examples of applications in fundamental condensed matter physics, materials science and technology

  13. Desorption of Te capping layer from ZnTe (100): Auger spectroscopy ...

    African Journals Online (AJOL)

    ... configurations of tellurium Te (c (2x2)) and Te (c (2x1)) are confirmed by scanning tunneling microscopy (STM). Such a study reveals a phase transition from a rich-Te to a poor-Te surface as the annealing temperature increases. Keywords: Zinc Tellure; solar cells; structural properties; optoelectronics; semiconductors.

  14. Dispersion of the second-order nonlinear susceptibility in ZnTe, ZnSe, and ZnS

    DEFF Research Database (Denmark)

    Wagner, Hans Peter; Kühnelt, M.; Langbein, Wolfgang Werner

    1998-01-01

    We have measured the absolute values of the second-harmonic generation (SHG) coefficient \\d\\ for the zinc-blende II-VI semiconductors ZnTe, ZnSe, and ZnS at room temperature. The investigated spectral region of the fundamental radiation lambda(F) ranges from 520 to 1321 nm using various pulsed...

  15. S and Te inter-diffusion in CdTe/CdS hetero junction

    Energy Technology Data Exchange (ETDEWEB)

    Enriquez, J. Pantoja [Cuerpo Academico-Energia y Sustentabilidad, Universidad Politecnica de Chiapas, Eduardo J. Selvas S/N, Col. Magisterial, Tuxtla Gutierrez 29010, Chiapas (Mexico); Gomez Barojas, E. [CIDS-ICUAP, Apdo. Postal 1651, 72000 Puebla (Mexico); Silva Gonzalez, R.; Pal, U. [Instituto de Fisica, Benemerita Universidad Autonoma de Puebla, Puebla (Mexico)

    2007-09-22

    Effects of post formation thermal annealing of the CdTe-CdS device on the inter-diffusion of S and Te at the junction in a substrate configuration device have been studied by Auger electron spectroscopy. While the migration of S and Te atoms increases with annealing temperature, the extent of S diffusion is always higher than the diffusion of Te atoms. Inter-diffusion of S and Te causes the formation of CdTe{sub 1-x}S{sub x} ternary compound at the CdTe-CdS interface. (author)

  16. Near-infrared emission bands of TeH and TeD

    Science.gov (United States)

    Fink, E. H.; Setzer, K. D.; Ramsay, D. A.; Vervloet, M.

    1989-11-01

    High-resolution emission spectra of TeH and TeD have been obtained in the region 4200 to 3600 cm -1 using a Bomem DA3.002 Fourier transform spectrometer. Analyses are given for the 0-0 and 1-1 bands of the X 22Π{1}/{2}-X 12Π{3}/{2} system of TeH and for the 0-0 band of TeD. In addition the 2-0 vibrational overtone bands of 130TeH, 128TeH, and 126TeH are observed and analyzed. Accurate molecular constants are given for the first time.

  17. Study of Te Inclusions in CdMnTe Crystals for Nuclear Detector Applications

    International Nuclear Information System (INIS)

    Babalola, O.S.; Bolotnikov, A.; Groza, M.; Hossain, A.; Egarievwe, S.; James, R.; Burger, A.

    2009-01-01

    The concentration, size and spatial distribution of Te inclusions in the bulk of CdMnTe crystals mined from two batches of ingots were studied. An isolated planar layer decorated with Te inclusions was identified in CdMnTe crystals from the second ingot. The internal electric field of a CMT crystal was probed by infrared (IR) imaging employing Pockels electro-optic effect. The effect of an isolated plane of Te inclusions on the internal electric-field distribution within the CdMnTe crystal was studied. Space charge accumulation around the plane of Te inclusions was observed, which was found to be higher when the detector was reverse-biased. The effects of the plane of Te inclusions on the electric-field distribution within the CdMnTe crystal, and the quality of CdMnTe crystals for nuclear detector applications are discussed.

  18. Liquidus surface of the triple reciprocal system PbTe+CdS↔PbS+CdTe

    International Nuclear Information System (INIS)

    Tomashik, Z.F.; Tomashik, V.N.

    1987-01-01

    Using differential-thermal and microstructural analyses and mathematical design interaction in PbTe-CdS system is studied. Liquidus surface of the triple reciprocal system PbTe+CdS↔PbS+CdTe is plotted. It is shown that PbTe-CdS system phase diagram is of eutectic type. Maximal solubility of CdS in PbTe attains 13 mol%, and of PbTe in CdS is not over 1 mol%. Projection of liquidus surface of the PbTe+CdS↔PbS+CdTe triple reciprocal system consists of two primary crystallization fields: CdTe x S 1-x and PbTe x S 1-x solid solutions separated by eutectic line

  19. MR imaging pulse sequence rationale: SD-, T1-, and T2-weighted images

    International Nuclear Information System (INIS)

    Sax, S.; Weathers, S.W.; Schneiders, N.J.; Horowitz, B.L.; Mawad, M.E.; Sandlin, M.E.; Blackwell, R.; Bryan, R.N.

    1986-01-01

    Over 500 patients have been examined with a pulse sequence designed to provide spin-density (SD)-weighted images (TR=3 sec, TE=35 msec), T1-weighted images (TR=0.3 sec, TE=35msec), and T2-weighted images (TR=3 sec, TE=105 msec) from which calculated ''synthesized'' images and SD, T1, and T2 calculated images could be obtained. Each image contributes unique information. SD-weighted images optimally display anatomy and often best highlight pathology. T1-weighted images are critical in assessing cerebral hemorrhages. T2-weighted images best display most lesions, but yield incomplete information in 35% of cases. All three types of ''weighted'' images are necessary to optimally display anatomy and fully characterize a lesion. Computerized calculations and simulations suggest that no other combination of pulse sequences yields equal information for a given examination time

  20. Particle acceleration by electromagnetic pulses

    International Nuclear Information System (INIS)

    Lai, H.M.

    1982-01-01

    Particle interaction with plane electromagnetic pulses is studied. It is shown that particle acceleration by a wavy pulse, depending on the shape of the pulse, may not be small. Further, a diffusive-type particle acceleration by multiple weak pulses is described and discussed. (author)

  1. Dynamics of traveling reaction pulses

    International Nuclear Information System (INIS)

    Dovzhenko, A. Yu.; Rumanov, E. N.

    2007-01-01

    The growth of activator losses is accompanied by the decay of a traveling reaction pulse. In a ring reactor, this propagation threshold is present simultaneously with a threshold related to the ring diameter. The results of numerical experiments with pulses of an exothermal reaction reveal the transition from pulse propagation to a homogeneous hot regime, established regimes with periodic variations of the pulse velocity, and oscillatory decay of the pulse. When the medium becomes 'bistable' as a result of the variation in parameters, this factor does not prevent the propagation of pulses, but leads to changes in the pulse structure

  2. Improvement of radiation response characteristic on CdTe detectors using fast neutron irradiation

    International Nuclear Information System (INIS)

    Miyamaru, Hiroyuki; Takahashi, Akito; Iida, Toshiyuki

    1999-01-01

    The treatment of fast neutron pre-irradiation was applied to a CdTe radiation detector in order to improve radiation response characteristic. Electron transport property of the detector was changed by the irradiation effect to suppress pulse amplitude fluctuation in risetime. Spectroscopic performance of the pre-irradiated detector was compared with the original. Additionally, the pre-irradiated detector was employed with a detection system using electrical signal processing of risetime discrimination (RTD). Pulse height spectra of 241 Am, 133 Ba, and 137 Cs gamma rays were measured to examine the change of the detector performance. The experimental results indicated that response characteristic for high-energy photons was improved by the pre-irradiation. The combination of the pre-irradiated detector and the RTD processing was found to provide further enhancement of the energy resolution. Application of fast neutron irradiation effect to the CdTe detector was demonstrated. (author)

  3. Solution Grown Se/Te Nanowires: Nucleation, Evolution, and The Role of Triganol Te seeds

    Directory of Open Access Journals (Sweden)

    Shan Xudong

    2009-01-01

    Full Text Available Abstract We have studied the nucleation and growth of Se–Te nanowires (NWs, with different morphologies, grown by a chemical solution process. Through systematic characterization of the Se–Te NW morphology as a function of the Te nanocrystallines (NCs precursor, the relative ratio between Se and Te, and the growth time, a number of significant insights into Se–Te NW growth by chemical solution processes have been developed. Specifically, we have found that: (i the growth of Se–Te NWs can be initiated from either long or short triganol Te nanorods, (ii the frequency of proximal interactions between nanorod tips and the competition between Se and Te at the end of short Te nanorods results in V-shaped structures of Se–Te NWs, the ratio between Se and Te having great effect on the morphology of Se–Te NWs, (iii by using long Te nanorods as seeds, Se–Te NWs with straight morphology were obtained. Many of these findings on Se–Te NW growth can be further generalized and provide very useful information for the rational synthesis of group VI based semiconductor NW compounds.

  4. Electrical properties of MIS devices on CdZnTe/HgCdTe

    Science.gov (United States)

    Lee, Tae-Seok; Jeoung, Y. T.; Kim, Hyun Kyu; Kim, Jae Mook; Song, Jinhan; Ann, S. Y.; Lee, Ji Y.; Kim, Young Hun; Kim, Sun-Ung; Park, Mann-Jang; Lee, S. D.; Suh, Sang-Hee

    1998-10-01

    In this paper, we report the capacitance-voltage (C-V) properties of metal-insulator-semiconductor (MIS) devices on CdTe/HgCdTe by the metalorganic chemical vapor deposition (MOCVD) and CdZnTe/HgCdTe by thermal evaporation. In MOCVD, CdTe layers are directly grown on HgCdTe using the metal organic sources of DMCd and DiPTe. HgCdTe layers are converted to n-type and the carrier concentration, ND is low 1015 cm-3 after Hg-vacancy annealing at 260 degrees Celsius. In thermal evaporation, CdZnTe passivation layers were deposited on HgCdTe surfaces after the surfaces were etched with 0.5 - 2.0% bromine in methanol solution. To investigate the electrical properties of the MIS devices, the C-V measurement is conducted at 80 K and 1 MHz. C-V curve of MIS devices on CdTe/HgCdTe by MOCVD has shown nearly flat band condition and large hysteresis, which is inferred to result from many defects in CdTe layer induced during Hg-vacancy annealing process. A negative flat band voltage (VFB approximately equals -2 V) and a small hysteresis have been observed for MIS devices on CdZnTe/HgCdTe by thermal evaporation. It is inferred that the negative flat band voltage results from residual Te4+ on the surface after etching with bromine in methanol solution.

  5. Partial Pressures of Te2 and Thermodynamic Properties of Ga-Te System

    Science.gov (United States)

    Su, Ching-Hua; Curreri, Peter A. (Technical Monitor)

    2001-01-01

    The partial pressures of Te2 in equilibrium with Ga(1-x)Te(x) samples were measured by optical absorption technique from 450 to 1100 C for compositions, x, between 0.333 and 0.612. To establish the relationship between the partial pressure of Te, and the measured optical absorbance, the calibration runs of a pure Te sample were also conducted to determine the Beer's Law constants. The partial pressures of Te2 in equilibrium with the GaTe(s) and Ga2Te3(s)compounds, or the so-called three-phase curves, were established. These partial pressure data imply the existence of the Ga3Te4(s) compound. From the partial pressures of Te2 over the Ga-Te melts, partial molar enthalpy and entropy of mixing for Te were derived and they agree reasonable well with the published data. The activities of Te in the Ga-Te melts were also derived from the measured partial pressures of Te2. These data agree well with most of the previous results. The possible reason for the high activity of Te measured for x less than 0.60 is discussed.

  6. Investigations of portable cadmium telluride (CdTe(Cl)) detectors for clinical studies with radioactive indicators

    International Nuclear Information System (INIS)

    Bojsen, J.

    1985-01-01

    The combination of small, portable γ-radiation-sensitive Cadmium Telluride (CdTE(Cl)) crystal detectors and portable solid state data storage memories makes it feasible to extend the measuring period in a number of clinical investigations based on the use of various radioisotopes and external detection. Blood sampling can be avoided in some cases. Continuous ambulatory monitoring of relevant physiological parameters is practicable, e.g. kidney function (GFR), left ventricular ejection fraction, subcutaneous blood flow, muscle blood flow and insulin absorption in diabetic patients. In the present methodological study the applicability of the 133-Xe washout technique to subcutaneous (s.c.) adipose tissue blood flow (SBF) has been investigated and adapted to the use of CdTe(Cl) detectors attached to the skin surface for the measurement of local 133-Xe-disappearance rate constants (k). Physical characterization of CdTe(Cl) detectors as γ-sensitive devices has been performed, and adequate counting sensitivities were found without detector energy-resolution properties. The CdTe(Cl) detectors are therefore suitable for single indicator studies. The measuring geometry of CdTe(Cl) detectors was studied and compared with that of stationary Sodium Iodide (NaI(Tl)) detectors in both phantom and in vivo investigations. The spatial properties of CdTe(Cl) detectors could to some extent be adjusted by pulse height discrimination and lead collimation. When long-term measurements were complicated by for instance physical activity of the patients, the small CdTe(Cl) detectors in general showed equal or better performance than the heavy and voluminous NaI(Tl) detectors. The free movement of the ambulatory patient and the avoidance of cable connections to stationary data-collecting systems gave improved possibilities for measurements of the relevant parameters. From this point of view, portable CdTe(Cl) detectors must be considered an important advance for radioactivity studies in

  7. Electrochemical Determination of Uric Acid at CdTe Quantum Dot Modified Glassy Carbon Electrodes.

    Science.gov (United States)

    Pan, Deng; Rong, Shengzhong; Zhang, Guangteng; Zhang, Yannan; Zhou, Qiang; Liu, Fenghai; Li, Miaojing; Chang, Dong; Pan, Hongzhi

    2015-01-01

    Cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical behavior of uric acid (UA) at a CdTe quantum dot (QD) modified the glassy carbon electrode (GCE). CdTe QDs, as new semiconductor nanocrystals, can greatly improve the peak current of UA. The anodic peak current of UA was linear with its concentration between 1.0×10(-6) and 4.0×10(-4) M in 0.1 M pH 5.0 phosphate buffer solution. The LOD for UA at the CdTe electrode (1.0×10(-7) M) was superior to that of the GCE. In addition, we also determined the effects of scan rate, pH, and interferences of UA for the voltammetric behavior and detection. The results indicated that modified electrode possessed excellent reproducibility and stability. Finally, a new and efficient electrochemical sensor for detecting UA was developed.

  8. Recent advances in Tl Br, Cd Te and CdZnTe semiconductor radiation detectors: a review

    International Nuclear Information System (INIS)

    Oliveira, Icimone B.

    2011-01-01

    The success in the development of radiation spectrometers operating at room temperature is based on many years of effort on the part of large numbers of workers around the world. These individuals have contributed to the understanding of the fundamental materials issues associated with the growth of semiconductors for this application, the development of device fabrication and processing technology, and advances in low noise electronics and pulse processing. Progress in this field continues at an accelerated pace, as in evidenced by the improvements in detector performance and by the growing number of commercial products. Thus, the last years have been seen continued effort in the development of room temperature compound semiconductors devices. High-Z compound semiconductor detectors has been explored for high energy resolution, high detection efficiency and are of low cost. Compound semiconductors detectors are well suited for addressing needs of demanding applications such as bore hole logging where high operating temperature are encountered. In this work recent developments in semiconductors detectors were reviewed. This review concentrated on thallium bromide (TlBr), cadmium zinc telluride (CdZnTe) and cadmium telluride (CdTe) crystals detectors. TlBr has higher stopping power compared to common semiconductor materials because it has the higher photoelectric and total attenuation coefficients over wide energy range from 100 keV to 1 MeV. CdTe and CdZnTe detectors have several attractive features for detecting X-ray and low energy gamma ray. Their relatively large band gaps lead to a relatively low leakage current and offer an excellent energy resolution at room temperature. A literature survey and bibliography was also included. (author)

  9. Recent advances in Tl Br, Cd Te and CdZnTe semiconductor radiation detectors: a review

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Icimone B. [Universidade Bandeirante (UNIBAN), Sao Paulo, SP (Brazil)

    2011-07-01

    The success in the development of radiation spectrometers operating at room temperature is based on many years of effort on the part of large numbers of workers around the world. These individuals have contributed to the understanding of the fundamental materials issues associated with the growth of semiconductors for this application, the development of device fabrication and processing technology, and advances in low noise electronics and pulse processing. Progress in this field continues at an accelerated pace, as in evidenced by the improvements in detector performance and by the growing number of commercial products. Thus, the last years have been seen continued effort in the development of room temperature compound semiconductors devices. High-Z compound semiconductor detectors has been explored for high energy resolution, high detection efficiency and are of low cost. Compound semiconductors detectors are well suited for addressing needs of demanding applications such as bore hole logging where high operating temperature are encountered. In this work recent developments in semiconductors detectors were reviewed. This review concentrated on thallium bromide (TlBr), cadmium zinc telluride (CdZnTe) and cadmium telluride (CdTe) crystals detectors. TlBr has higher stopping power compared to common semiconductor materials because it has the higher photoelectric and total attenuation coefficients over wide energy range from 100 keV to 1 MeV. CdTe and CdZnTe detectors have several attractive features for detecting X-ray and low energy gamma ray. Their relatively large band gaps lead to a relatively low leakage current and offer an excellent energy resolution at room temperature. A literature survey and bibliography was also included. (author)

  10. B-factory via conversion of 1-TeV electron beams into 1-TeV photon beams

    International Nuclear Information System (INIS)

    Mtingwa, S.K.

    1991-01-01

    This paper reports on the study of CP violation and rare decays of beauty particles which are pressing problems in high-energy physics. It is known that one should analyze beauty decays of at least the order of 10 8 or 19 9 . Thus, numerous proposals for beauty factories are being discussed now, although some of these projects are likely to supply much smaller numbers of beauty events. At the same time, at present several projects, such as CLIC (Cern Linear Collider), expect to build linear e + e - colliders with beam energies up to 1 TeV. The aim of this work is to show that the possibility exists of using the unique features of the discussed teraelectron volt electron linacs to obtain a facility for the production of beauty via photoproduction of nuclei. Unique features of high-energy photoproduction are as follows. The rather large fraction (∼2 x 10 -4 ) of events with beauty at E γ ∼ 1 TeV. Beauty particles are produced with about equally large momenta ∼0.05 E γ and at rather large transverse momenta p t ∼ m b . The following scheme can be envisioned. The 1-TeV electron beam is Compton scattered off a low-energy (∼ 1-eV) laser pulse. The laser photons are thus converted into a highly collimated beam of energy E γ ∼ E e , directed along the electron's original line of motion. Such schemes to produce high-energy photon beams have been discussed. These 1-TeV photons are subsequently scattered onto a nuclear target to produce b bar b pairs

  11. Nonlinear absorption and transmission properties of Ge, Te and InAs using tuneable IR FEL

    Energy Technology Data Exchange (ETDEWEB)

    Amirmadhi, F.; Becker, K.; Brau, C.A. [Vanderbilt Univ., Nashville, TN (United States)

    1995-12-31

    Nonlinear absorption properties of Ge, Te and InAs are being investigated using the transmission of FEL optical pulses through these semiconductors (z-scan method). Wavelength, intensity and macropulse dependence are used to differentiate between two-photon and free-carrier absorption properties of these materials. Macropulse dependence is resolved by using a Pockles Cell to chop the 4-{mu}s macropulse down to 100 ns. Results of these experiments will be presented and discussed.

  12. Thermochemical properties of silver tellurides including empressite (AgTe) and phase diagrams for Ag-Te and Ag-Te-O

    Science.gov (United States)

    Voronin, Mikhail V.; Osadchii, Evgeniy G.; Brichkina, Ekaterina A.

    2017-10-01

    This study compiles original experimental and literature data on the thermodynamic properties (ΔfG°, S°, ΔfH°) of silver tellurides (α-Ag2Te, β-Ag2Te, Ag1.9Te, Ag5Te3, AgTe) obtained by the method of solid-state galvanic cell with the RbAg4I5 and AgI solid electrolytes. The thermodynamic data for empressite (AgTe, pure fraction from Empress Josephine Mine, Colorado USA) have been obtained for the first time by the electrochemical experiment with the virtual reaction Ag + Te = AgTe. The Ag-Te phase diagrams in the T - x and log fTe2 (gas) - 1/ T coordinates have been refined, and the ternary Ag-Te-O diagrams with Ag-Te-TeO2 (paratellurite) composition range have been calculated.

  13. n-(CdMgTe/CdTe)/(p-(CdTe/ZnCdTe/ZnTe)/p-GaAs heterostructure diode for photosensor applications

    Science.gov (United States)

    Yahia, I. S.; AlFaify, S.; Abutalib, M. M.; Chusnutdinow, S.; Wojtowicz, T.; Karczewski, G.; Yakuphanoglu, F.; Al-Bassam, A.; El-Naggar, A. M.; El-Bashir, S. M.

    2016-05-01

    High quality n-(CdMgTe:I/n-CdTe:I)/(p-CdTe:N/p-ZnCdTe:N/p-ZnTe:N)/p-GaAs heterojunction diodes have been fabricated by molecular beam epitaxial growth. The illumination effect on the complex impedance and conductivity of heterostructure diode was investigated. The illumination intensities were taken up to the 200 mW/cm2 with frequency range of 42 Hz to 1 MHz. The observed real and imaginary parts of the complex impedance were strongly dependent on the illumination frequency. The inverse relation was observed between the illumination intensity and the complex impedance. The relaxation mechanism of the diode was analyzed by the Cole-Cole plots. The radius of the Cole-Cole curve decreases with increasing illumination intensity. This suggests a mechanism of illumination dependent on the relaxation process. It is also found that the conductivity increases linearly with increasing the illumination intensity. We can conclude that the new design heterostructure diode in our work is a good candidate in photodetector and optoelectronic applications.

  14. Pulsed rf excited spectrometer having improved pulse width control

    International Nuclear Information System (INIS)

    1977-01-01

    RF excitation for a spectrometer is obtained by pulse width modulating an RF carrier to produce the desired broadband RF exciting spectrum. The RF excitation includes a train of composite RF pulses, each composite pulse having a primary pulse portion of a first RF phase and a second pulse portion of a second RF phase opposite that of the first. In this manner, the finite rise and fall times of the primary pulse portion are compensated for by the corresponding rise and fall times of the secondary pulse portion. The primary pulse portion is lengthened by an amount equal to the secondary pulse portion so that the secondary pulse portion cancels the added primary pulse portion. In a spectrometer, the compensating second pulse component removes certain undesired side bands of the RF excitation caused by the finite rise and fall times of the applied RF pulses. The compensating second pulse component removes certain undesired side bands associated with each of the resonant lines of the excited resonance spectrum of the sample under analysis, particularly for wide band RF excitation

  15. Electrically induced phase transition in GeSbTe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bruns, Gunnar; Schlockermann, Carl; Woda, Michael; Wuttig, Matthias [I. Physikalisches Institut Ia, RWTH Aachen, 52056 Aachen (Germany)

    2008-07-01

    While phase change materials have already successfully been applied in rewriteable optical data storage, they are now also promising to form the basis for novel non-volatile electrical data storage devices. To understand the physical concepts of these so-called Phase Change Random Access Memory (PCRAM) it is mandatory to gain a deeper insight into the switching process between the highly resistive amorphous and the lowly resistive crystalline phase. The fast phase transitions between the amorphous and crystalline state of GeSbTe-based alloys has so far often been studied using pulsed laser irradiation. In this work an alternative approach is employed to investigate this transition. Electrical pulses are used to rapidly and reversibly switch between the two states. For these experiments a setup was built with a specially designed contacting circuit board to meet the requirements of electrical measurements on a nanosecond timescale. The influence of the pulse parameters on the change of device resistance was determined for different initial states. Furthermore the high time resolution of 0.4 ns allows investigation of transient electrical effects like the so-called threshold switching first described by Ovshinsky in the late 1960s.

  16. Electrically induced phase transition in GeSbTe alloys

    International Nuclear Information System (INIS)

    Bruns, Gunnar; Schlockermann, Carl; Woda, Michael; Wuttig, Matthias

    2008-01-01

    While phase change materials have already successfully been applied in rewriteable optical data storage, they are now also promising to form the basis for novel non-volatile electrical data storage devices. To understand the physical concepts of these so-called Phase Change Random Access Memory (PCRAM) it is mandatory to gain a deeper insight into the switching process between the highly resistive amorphous and the lowly resistive crystalline phase. The fast phase transitions between the amorphous and crystalline state of GeSbTe-based alloys has so far often been studied using pulsed laser irradiation. In this work an alternative approach is employed to investigate this transition. Electrical pulses are used to rapidly and reversibly switch between the two states. For these experiments a setup was built with a specially designed contacting circuit board to meet the requirements of electrical measurements on a nanosecond timescale. The influence of the pulse parameters on the change of device resistance was determined for different initial states. Furthermore the high time resolution of 0.4 ns allows investigation of transient electrical effects like the so-called threshold switching first described by Ovshinsky in the late 1960s

  17. High-Power Plasma Switch for 11.4 GHz Microwave Pulse Compressor

    International Nuclear Information System (INIS)

    Hirshfield, Jay L.

    2010-01-01

    Results obtained in several experiments on active RF pulse compression at X-band using a magnicon as the high-power RF source are presented. In these experiments, microwave energy was stored in high-Q TE01 and TE02 modes of two parallel-fed resonators, and then discharged using switches activated with rapidly fired plasma discharge tubes. Designs and high-power tests of several versions of the compressor are described. In these experiments, coherent pulse superposition was demonstrated at a 5-9 MW level of incident power. The compressed pulses observed had powers of 50-70 MW and durations of 40-70 ns. Peak power gains were measured to be in the range of 7:1-11:1 with efficiency in the range of 50-63%.

  18. Scandium doping brings speed improvement in Sb2Te alloy for phase change random access memory application.

    Science.gov (United States)

    Chen, Xin; Zheng, Yonghui; Zhu, Min; Ren, Kun; Wang, Yong; Li, Tao; Liu, Guangyu; Guo, Tianqi; Wu, Lei; Liu, Xianqiang; Cheng, Yan; Song, Zhitang

    2018-05-01

    Phase change random access memory (PCRAM) has gained much attention as a candidate for nonvolatile memory application. To develop PCRAM materials with better properties, especially to draw closer to dynamic random access memory (DRAM), the key challenge is to research new high-speed phase change materials. Here, Scandium (Sc) has been found it is helpful to get high-speed and good stability after doping in Sb 2 Te alloy. Sc 0.1 Sb 2 Te based PCRAM cell can achieve reversible switching by applying even 6 ns voltage pulse experimentally. And, Sc doping not only promotes amorphous stability but also improves the endurance ability comparing with pure Sb 2 Te alloy. Moreover, according to DFT calculations, strong Sc-Te bonds lead to the rigidity of Sc centered octahedrons, which may act as crystallization precursors in recrystallization process to boost the set speed.

  19. Herophilus on pulse

    Directory of Open Access Journals (Sweden)

    Afonasin, Eugene

    2015-01-01

    Full Text Available The first detailed study of the pulse (sphygmology is associated in antiquity with Herophilus (the end of the 4th century BCE, an Alexandrian physician, renowned for his anatomical discoveries. The scholars also attribute to him a discovery of a portable and adjustable water-clock, used for measuring ‘natural’ and ‘unnatural’ pulse and, accordingly, temperature of the patient. In the article we translate the principal ancient evidences and comment upon them. We study both the practical aspects of ancient sphygmology and the theoretical speculations associated with it. Ancient theory of proportion and musical harmony allowed to build a classification of the pulses, but the medical experience did not fit well in the Procrustean bed of this rather simple theory.

  20. Current Extensions on PULSE

    Directory of Open Access Journals (Sweden)

    Sanda Dragos

    2010-09-01

    Full Text Available Using a learning management system (LMS is a common practise nowadays. Such instruments are used in educational institutions to enhance and support the teaching act as well as in industry for training purposes. In a computer science department of an university such instrument tends to be a basic requirement. That is because not only it allows a better management of courses and a better communication between students and professors, but can also serve as a perfect instrument for presenting teaching related materials for computer science subjects. During the years I have created and used several such instruments: a System with Interactive ackNowledgement and Evaluation of students work during laboratory sessions (SINE, a Php Utility used in Laboratories for Student Evaluation (PULSE, and PULSE Extended. The aim of this paper is to present the current enhancements of PULSE.

  1. TE Wave Measurement and Modeling

    CERN Document Server

    Sikora, John P; Sonnad, Kiran G; Alesini, David; De Santis, Stefano

    2013-01-01

    In the TE wave method, microwaves are coupled into the beam-pipe and the effect of the electron cloud on these microwaves is measured. An electron cloud (EC) density can then be calculated from this measurement. There are two analysis methods currently in use. The first treats the microwaves as being transmitted from one point to another in the accelerator. The second more recent method, treats the beam-pipe as a resonant cavity. This paper will summarize the reasons for adopting the resonant TE wave analysis as well as give examples from CESRTA and DA{\\Phi}NE of resonant beam-pipe. The results of bead-pull bench measurements will show some possible standing wave patterns, including a cutoff mode (evanescent) where the field decreases exponentially with distance from the drive point. We will outline other recent developments in the TE wave method including VORPAL simulations of microwave resonances, as well as the simulation of transmission in the presence of both an electron cloud and magnetic fields.

  2. Upgrade of the SLAC SLED II Pulse Compression System Based on Recent High Power Tests

    International Nuclear Information System (INIS)

    Vlieks, A.E.; Fowkes, W.R.; Loewen, R.J.; Tantawi, S.G.

    2011-01-01

    In the Next Linear Collider (NLC) it is expected that the high power rf components be able to handle peak power levels in excess of 400 MW. We present recent results of high power tests designed to investigate the RF breakdown limits of the X-band pulse compression system used at SLAC. (SLED-II). Results of these tests show that both the TE 01 -TE 10 mode converter and the 4-port hybrid have a maximum useful power limit of 220-250 MW. Based on these tests, modifications of these components have been undertaken to improve their peak field handling capability. Results of these modifications will be presented. As part of an international effort to develop a new 0.5-1.5 TeV electron-positron linear collider for the 21st century, SLAC has been working towards a design, referred to as 'The Next Linear Collider' (NLC), which will operate at 11.424 GHz and utilize 50-75 MW klystrons as rf power sources. One of the major challenges in this design, or any other design, is how to generate and efficiently transport extremely high rf power from a source to an accelerator structure. SLAC has been investigating various methods of 'pulse compressing' a relatively wide rf pulse ((ge) 1 μs) from a klystron into a narrower, but more intense, pulse. Currently a SLED-II pulse compression scheme is being used at SLAC in the NLC Test Accelerator (NLCTA) and in the Accelerator Structures Test Area (ASTA) to provide high rf power for accelerator and component testing. In ASTA, a 1.05 μs pulse from a 50 MW klystron was successfully pulse compressed to 205 MW with a pulse width of 150 ns. Since operation in NLC will require generating and transporting rf power in excess of 400 MW it was decided to test the breakdown limits of the SLED-II rf components in ASTA with rf power up to the maximum available of 400 MW. This required the combining of power from two 50 MW klystrons and feeding the summed power into the SLED-II pulse compressor. Results from this experiment demonstrated that two of

  3. Highest-order optical phonon-mediated relaxation in CdTe/ZnTe quantum dots

    International Nuclear Information System (INIS)

    Masumoto, Yasuaki; Nomura, Mitsuhiro; Okuno, Tsuyoshi; Terai, Yoshikazu; Kuroda, Shinji; Takita, K.

    2003-01-01

    The highest 19th-order longitudinal optical (LO) phonon-mediated relaxation was observed in photoluminescence excitation spectra of CdTe self-assembled quantum dots grown in ZnTe. Hot excitons photoexcited highly in the ZnTe barrier layer are relaxed into the wetting-layer state by emitting multiple LO phonons of the barrier layer successively. Below the wetting-layer state, the LO phonons involved in the relaxation are transformed to those of interfacial Zn x Cd 1-x Te surrounding CdTe quantum dots. The ZnTe-like and CdTe-like LO phonons of Zn x Cd 1-x Te and lastly acoustic phonons are emitted in the relaxation into the CdTe dots. The observed main relaxation is the fast relaxation directly into CdTe quantum dots and is not the relaxation through either the wetting-layer quantum well or the band bottom of the ZnTe barrier layer. This observation shows very efficient optical phonon-mediated relaxation of hot excitons excited highly in the ZnTe conduction band through not only the ZnTe extended state but also localized state in the CdTe quantum dots reflecting strong exciton-LO phonon interaction of telluride compounds

  4. Millimicrosecond pulse techniques

    CERN Document Server

    Lewis, Ian A D

    1959-01-01

    Millimicrosecond Pulse Techniques, Second Edition focuses on millimicrosecond pulse techniques and the development of devices of large bandwidth, extending down to comparatively low frequencies (1 Mc/s). Emphasis is on basic circuit elements and pieces of equipment of universal application. Specific applications, mostly in the field of nuclear physics instrumentation, are considered. This book consists of eight chapters and opens with an introduction to some of the terminology employed by circuit engineers as well as theoretical concepts, including the laws of circuit analysis, Fourier analysi

  5. Pulsed Plasma Electron Sources

    Science.gov (United States)

    Krasik, Yakov

    2008-11-01

    Pulsed (˜10-7 s) electron beams with high current density (>10^2 A/cm^2) are generated in diodes with electric field of E > 10^6 V/cm. The source of electrons in these diodes is explosive emission plasma, which limits pulse duration; in the case E Saveliev, J. Appl. Phys. 98, 093308 (2005). Ya. E. Krasik, A. Dunaevsky, and J. Felsteiner, Phys. Plasmas 8, 2466 (2001). D. Yarmolich, V. Vekselman, V. Tz. Gurovich, and Ya. E. Krasik, Phys. Rev. Lett. 100, 075004 (2008). J. Z. Gleizer, Y. Hadas and Ya. E. Krasik, Europhysics Lett. 82, 55001 (2008).

  6. Spallation neutrons pulsed sources

    International Nuclear Information System (INIS)

    Carpenter, J.

    1996-01-01

    This article describes the range of scientific applications which can use these pulsed neutrons sources: Studies on super fluids, measures to verify the crawling model for the polymers diffusion; these sources are also useful to study the neutron disintegration, the ultra cold neutrons. In certain applications which were not accessible by neutrons diffusion, for example, radiations damages, radionuclides production and activation analysis, the spallation sources find their use and their improvement will bring new possibilities. Among others contributions, one must notice the place at disposal of pulsed muons sources and neutrinos sources. (N.C.). 3 figs

  7. Pulse Doppler radar

    CERN Document Server

    Alabaster, Clive

    2012-01-01

    This book is a practitioner's guide to all aspects of pulse Doppler radar. It concentrates on airborne military radar systems since they are the most used, most complex, and most interesting of the pulse Doppler radars; however, ground-based and non-military systems are also included. It covers the fundamental science, signal processing, hardware issues, systems design and case studies of typical systems. It will be a useful resource for engineers of all types (hardware, software and systems), academics, post-graduate students, scientists in radar and radar electronic warfare sectors and milit

  8. Pulse Synchronization System (PSS)

    International Nuclear Information System (INIS)

    1977-06-01

    This document is intended to serve as an operations manual, as well as a documentation of the backup analyses pertinent to the design as delivered. A history of earlier unsuccessful versions of the Pulse Synchronization System (PSS) is not included. The function of the PSS is to synchronize the time of arrival at the fusion target of laser pulses that are propagated through the 20 amplifier chains of the SHIVA laser. The positional accuracy requirement is +-1.5 mm (+-5 psec), and is obtained by the PSS with a wide margin factor

  9. Physical model of reactor pulse

    International Nuclear Information System (INIS)

    Petrovic, A.; Ravnik, M.

    2004-01-01

    Pulse experiments have been performed at J. Stefan Institute TRIGA reactor since 1991. In total, more than 130 pulses have been performed. Extensive experimental information on the pulse physical characteristics has been accumulated. Fuchs-Hansen adiabatic model has been used for predicting and analysing the pulse parameters. The model is based on point kinetics equation, neglecting the delayed neutrons and assuming constant inserted reactivity in form of step function. Deficiencies of the Fuchs-Hansen model and systematic experimental errors have been observed and analysed. Recently, the pulse model was improved by including the delayed neutrons and time dependence of inserted reactivity. The results explain the observed non-linearity of the pulse energy for high pulses due to finite time of pulse rod withdrawal and the contribution of the delayed neutrons after the prompt part of the pulse. The results of the improved model are in good agreement with experimental results. (author)

  10. Electrodeposition of textured Bi27Sb28Te45 nanowires with enhanced electrical conductivity

    International Nuclear Information System (INIS)

    Hasan, Maksudul; Gautam, Devendraprakash; Enright, Ryan

    2016-01-01

    This work presents the template based pulsed potential electrodeposition technique of highly textured single crystalline bismuth antimony telluride (Bi 1-x Sb x ) 2 Te 3 nanowires from a single aqueous electrolyte. Cyclic voltammetry was used as an electroanalytical tool to assess the effect of the precursor concentrations on the composition of the deposits and to determine the deposition potential for each element. Pulsed potential electrodeposition was then applied on a gold-coated anodised alumina template to examine the effect of the pulse parameters on the composition and texture of Bi 27 Sb 28 Te 45 nanowires. The nanowires are cylindrical in shape formed during the deposition inside the porous template and highly textured as they are decorated with sparse distribution of small crystal domains. The electrical conductivity (24.1 × 10 4  S m −1 ) of a single nanowire was measured using a four-point probe technique implemented on a custom fabricated test chip. In this work, we demonstrated that crystal orientation with respect to the transport direction controlled by tuning the pulsed electrodeposition parameters. This allowed us to realise electrical conductivities ∼2.5 times larger than Sb doped bismuth-tellurium based ternary material systems and similar to what is typically seen in binary systems. - Highlights: • Pulsed electrodeposition is described towards fabrication of (Bi 1-x Sb x ) 2 Te 3 nanowires. • The adopted method is compatible with existing CMOS process. • The nanowires were fabricated as highly textured to enhance phonon scattering. • The electrical conductivity is ∼2.5 times larger than the current ternary materials.

  11. Piezoelectric effect in CdTe/CdMnTe and CdTe/CdZnTe quantum wells

    International Nuclear Information System (INIS)

    Andre, Regis

    1994-01-01

    Materials with zinc-blende type structure are piezoelectric: any strain along a polar axis generates an electrical polarisation. Strained quantum wells of cubic II-VI or III-V semiconductors, grown along [111] or [112] axis, exhibit a strong built-in piezo-electric field (100 kV/cm for 1% strains). Such structures are very promising for applications to optical modulation, but it is necessary to study first the physical properties of piezoelectric heterostructures before they can be used in optical devices. For this purpose, we have performed an optical study of strained CdTe/CdMnTe or CdTe/CdZnTe quantum wells coherently grown by molecular beam epitaxy on [111] or [112] oriented substrates. Effects of piezoelectric field on optical and electronic properties of quantum wells have been analyzed in terms of the envelop function model, taking into account the effects of biaxial strains for [hhk] growth axis. Moreover, we have proposed an original way of measuring piezoelectric field in strained quantum wells, and we have used this method to show that CdTe exhibits strong non-linearities for piezoelectric field versus strain. This effect has never been mentioned before. We have also performed measurements of the piezoelectric coefficient e14 under high hydrostatic pressure inducing strains up to 2%, which shows that part of the non-linear effect is a volume effect. We have also studied the effects of the piezoelectric field on excitons in quantum wells. The binding energy decreases slightly when the electric field increases, but the oscillator strength, for the fundamental transition, decreases dramatically with the overlap of the envelope wavefunctions of electrons and holes. We have performed a modelization of an exciton in a piezoelectric quantum well using two variational parameters. This model provides an accurate calculation of excitonic absorption. Our experimental and theoretical results are in very good agreement, without any fitting parameters, for a large

  12. Partial enthalpies of Bi and Te in Bi-Te melts and of In and Te in In-Te melts

    International Nuclear Information System (INIS)

    Yassin, Abeer; Amzil, Abdelhamid; Castanet, Robert

    2000-01-01

    Full text.Calorimetric measurement are reported which allow the enthalpic behaviour of Bi-Te melts to be established. Further work is required, however, to supplement results obtained for In-Te melts. The partial enthalpies of bismuth and tellurium in the Bi-Te melts at 755K and those of indium and tellurium in the In-Te melts at 1010 and 987K were measured at high dilution by direct reaction calorimetry (drop method) with the help of a Tian-Calvet calorimeter. The limiting partial enthalpies of the components were deduced by extrapolation at infinite dilution: Δh f,∞ B i(755K)/KJ.mol -1 = -34.0 and Δh f,∞ Te(755K) /KJ·mol -1 = -24.1 in the Bi-Te melts Δh f,∞ In(1010K) /KJ·mol -1 = -75.9 and Δh f,∞ Te(1010K) /KJ·mol -1 = -47.8 in the In-Te melts Δh f,∞ In(987K) /KJ·mol -1 = -75.2 and Δh f,∞ Te(987K) /KJ·mol -1 = -48.0 in the In-Te melts

  13. Pulse power modulators - an overview

    International Nuclear Information System (INIS)

    Venkatramani, N.

    2006-01-01

    Pulse power modulators are electronic devices to provide, high voltage, high current, power bursts. Ideally, a modulator, with the means to shape and control the pulses, acts as a switch between a high voltage power supply and its load. This article gives an overview of the pulse power modulators: starting with the basics of pulse and modulation, it covers modulation topologies, different types of modulators, major subsystems and pulse measurement techniques. The various applications of pulse power modulators and the recent trends have been included at the end. (author)

  14. Proton Pulse Radiolysis

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, H C; Nilsson, G; Reitberger, T; Thuomas, K A

    1973-03-15

    A 5 MeV proton accelerator (Van de Graaff) has been used for pulse radiolysis of a number of organic gases and the transient spectra obtained from the alkanes methane, ethane, propane, n-butane and neopentane have tentatively been assigned to alkyl radicals. Some methodological aspects of this new technique are discussed

  15. Lectures on pulsed NMR

    International Nuclear Information System (INIS)

    Pines, A.

    1988-08-01

    These lectures discuss some recent developments in pulsed NMR, emphasizing fundamental principles with selected illustrative applications. Major topics covered include multiple-quantum spectroscopy, spin decoupling, the interaction of spins with a quantized field, adiabatic rapid passage, spin temperature and statistics of cross-polarization, coherent averaging, and zero field NMR. 32 refs., 56 figs

  16. Lectures on pulsed NMR

    International Nuclear Information System (INIS)

    Pines, A.

    1986-09-01

    These lectures discuss some recent developments in pulsed NMR, emphasizing fundamental principles with selected illustrative applications. Major topics covered include multiple-quantum spectroscopy, spin decoupling, the interaction of spins with a quantized field, adiabatic rapid passage, spin temperature and statistics of cross-polarization, coherent averaging, and zero field NMR. 55 figs

  17. Pulsed electric fields

    Science.gov (United States)

    The concept of pulsed electric fields (PEF) was first proposed in 1967 to change the behavior or microorganisms. The electric field phenomenon was identified as membrane rupture theory in the 1980s. Increasing the membrane permeability led to the application of PEF assisted extraction of cellular co...

  18. Pulsed inductive HF laser

    Energy Technology Data Exchange (ETDEWEB)

    Razhev, A M; Kargapol' tsev, E S [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Churkin, D S; Demchuk, S V [Novosibirsk State University, Novosibirsk (Russian Federation)

    2016-03-31

    We report the results of experimentally investigated dependences of temporal, spectral and spatial characteristics of an inductive HF-laser generation on the pump conditions. Gas mixtures H{sub 2} – F{sub 2}(NF{sub 3} or SF6{sub 6}) and He(Ne) – H{sub 2} – F{sub 2}(NF{sub 3} or SF{sub 6}) were used as active media. The FWHM pulse duration reached 0.42 μs. This value corresponded to a pulsed power of 45 kW. For the first time, the emission spectrum of an inductive HF laser was investigated, which consisted of seven groups of bands with centres around the wavelengths of 2732, 2736, 2739, 2835, 2837, 2893 and 2913 nm. The cross section profile of the laser beam was a ring with a diameter of about 20 mm and width of about 5 mm. Parameters of laser operation in the repetitively pulsed regime were sufficiently stable. The amplitude instability of light pulses was no greater than 5% – 6%. (lasers)

  19. Intense microwave pulse propagation through gas breakdown plasmas in a waveguide

    International Nuclear Information System (INIS)

    Byrne, D.P.

    1986-01-01

    High-power microwave pulse-compression techniques are used to generate 2.856 GHz pulses which are propagated in a TE 10 mode through a gas filled section of waveguide, where the pulses interact with self-generated gas-breakdown plasmas. Pulse envelopes transmitted through the plasmas, with duration varying from 2 ns to greater than 1 μs, and peak powers of a few kW to nearly 100 MW, are measured as a function of incident pulse and gas pressure for air, nitrogen, and helium. In addition, the spatial and temporal development of the optical radiation emitted by the breakdown plasmas are measured. For transmitted pulse durations ≥ 100 ns, good agreement is found with both theory and existing measurements. For transmitted pulse duration as short as 2 ns (less than 10 rf cycles), a two-dimensional model is used in which the electrons in the plasma are treated as a fluid whose interactions with the microwave pulse are governed by a self-consistent set of fluid equations and Maxwell's equations for the electromagnetic field. The predictions of this model for air are compared with the experimental results over a pressure range of 0.8 torr to 300 torr. Good agreement is obtained above about 1 torr pressure, demonstrating that microwave pulse propagation above the breakdown threshold can be accurately modeled on this time scale. 63 refs., 44 figs., 2 tabs

  20. Pulsed laser deposition of II-VI and III-V semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Mele, A.; Di Palma, T.M.; Flamini, C.; Giardini Guidoni, A. [Rome, Univ. `La Sapienza` (Italy). Dep. di Chimica

    1998-12-01

    Pulsed laser irradiation of a solid target involves electronic excitation and heating, followed by expansion from the target of the elliptical gas cloud (plume) which can be eventually condensed on a suitable substrate. Pulsed laser ablation has been found to be a valuable technique to prepare II-VI and III-V thin films of semiconductor materials. Pulsed laser ablation deposition is discussed in the light of the results of an investigation on CdS, CdSe, CdTe and CdSe/CdTe multilayers and AIN, GaN and InN together with Al-Ga-In-N heterostructures. [Italiano] L`irradiazione di un target solido, mediante un fascio laser impulsato, genera una serie di processi che possono essere schematizzati come segue: riscaldamento ed eccitazione elettronica del target, da cui consegue l`espulsione di materiale sotto forma di una nube gassosa di forma ellissoidale (plume), che espande e puo` essere fatta depositare su un opportuno substrato. L`ablazione lasersi e` rivelata una tecnica valida per preparare film sottili di composti di elementi del II-VI e del III-V gruppo della tavola periodica. La deposizione via ablazione laser viene discussa alla luce dei risultati ottenuti nella preparazione di film di CdS, CdSe, CdTe e di film multistrato di CdSe/CdTe, di film di AIN, GaN, InN e di eterostrutture di Al-Ga-In-N.

  1. Surface passivation for CdTe devices

    Energy Technology Data Exchange (ETDEWEB)

    Reese, Matthew O.; Perkins, Craig L.; Burst, James M.; Gessert, Timothy A.; Barnes, Teresa M.; Metzger, Wyatt K.

    2017-08-01

    In one embodiment, a method for surface passivation for CdTe devices is provided. The method includes adjusting a stoichiometry of a surface of a CdTe material layer such that the surface becomes at least one of stoichiometric or Cd-rich; and reconstructing a crystalline lattice at the surface of the CdTe material layer by annealing the adjusted surface.

  2. Superconducting transition in TlBiTe/sub 2/ and TlTe compounds

    Energy Technology Data Exchange (ETDEWEB)

    Kantser, V G; Popovich, N S; Sidorenko, A S

    1985-10-01

    On the basis of zone structure calculation for TlBiTe/sub 2/ and TlTe it is found that TlBiTe/sub 2/ is a narrow-gap semiconductor and TlTe is a p-metal. At Tsub(c)=0.19 K TlTe is found to experience the superconducting transition. In TlBiTe/sub 2/ superconductivity is not observed to occur up to 0.05 K, since there is a possibility of occupying the high density of states zones because they are remote from actual ones. The earlier discovered superconducting transition in TlBiTe/sub 2/ is inherent in the alien phase of TlTe.

  3. Sequentially pulsed traveling wave accelerator

    Science.gov (United States)

    Caporaso, George J [Livermore, CA; Nelson, Scott D [Patterson, CA; Poole, Brian R [Tracy, CA

    2009-08-18

    A sequentially pulsed traveling wave compact accelerator having two or more pulse forming lines each with a switch for producing a short acceleration pulse along a short length of a beam tube, and a trigger mechanism for sequentially triggering the switches so that a traveling axial electric field is produced along the beam tube in synchronism with an axially traversing pulsed beam of charged particles to serially impart energy to the particle beam.

  4. On the mean square displacements (MSD) of Hg and Te in HgTe

    International Nuclear Information System (INIS)

    Madhavan, Y.; Ramachandran, K.

    1989-01-01

    The mean square displacements (MSD) of Hg and Te in the perfect system of HgTe are worked out in the modified rigid ion model of Plumelle and Vandevyver. Also the MSD of Hg and Te neighbours around anion and cation vacancies in HgTe are worked out giving an active role for the vacancy following the theory of Maradudin et al. The results are compared with experimental values. (author)

  5. The crystal structures and powder diffraction patterns of the uranium tellurides

    Energy Technology Data Exchange (ETDEWEB)

    Snyder, R.L. (State Univ. of New York, Alfred, NY (USA). Inst. of Ceramic Superconductivity); Nichols, M.C.; Boehme, D.R. (Sandia National Labs., Livermore, CA (USA))

    1990-10-03

    A critical review of all of the reported structures and powder diffraction patterns in the uranium telluride system has been undertaken. Structures that are correct: Cubic -- UTe: no experimental pattern exists. Retain calculated 15--865. Cubic --U{sub 3}Te{sub 4}: retain the poor quality 12--610 but adopt the pattern calculated here. Cubic U{sub 2}Te{sub 3}: no experimental pattern exists. Adopt pattern calculated here. Orthorhombic UTe{sub 2}: Adopt the new pattern of Boehme et al. Monoclinic {alpha}UTe{sub 3} Adopt the new pattern of Boehme et al. Monoclinic {alpha}UTe{sub 3} Adopt the new pattern of Boehme et al. Orthorhombic {beta}UTe{sub 3}: Adopt pattern calculated here. Orthorhombic UTe{sub 5}: Adopt the new pattern of Boehme et al. Structures in need of refinement: Orthorhombic U{sub 2}Te{sub 3}:Adopt pattern calculated here over 34--807. Hexagonal U{sub 7}Te{sub 12}: Adopt pattern calculated here but retain 24--1368. Orthorhombic UTe{sub 1.78}: Adopt pattern calculated here and retain our modified 21--1404 reported for U{sub 4}Te{sub 7}. Orthorhombic UTe{sub 2.5}: Adopt pattern calculated here. Orthorhombic UTe{sub 3.4}: Accept recent pattern of Boehme et al. Phases for which no structures or reliable patterns exist: Orthorhombic U{sub 3}Te{sub 4}: no published pattern. Tetragonal U{sub 3}Te{sub 5}: three patterns 21--1407, 34--766 and 34--896 exit but all are of very poor quality. Phases which probably do not exist: Tetragonal UTe{sub 1.78}, Tetragonal UTe{sub 2}, Cubic UTe{sub 2} U{sub 3}Te{sub 7}(21--1402), U{sub 3}Te{sub 8}(21--1406).

  6. Pulse pile-up IV

    International Nuclear Information System (INIS)

    Wilkinson, D.H.

    1991-05-01

    The study of pulse pile-up is extended from the case of unipolar pulses, for which ruin theory is an excellent approximation, to the case of bipolar pulses for which ruin theory is not applicable to the effect of the back-kicks in reducing the pile-up: an appropriate solution is presented. (Author) 3 refs., 11 figs

  7. In situ study on the formation of FeTe

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Wulff, Anders Christian; Yue, Zhao

    2011-01-01

    The formation of the FeTe compound from a mixture of Fe and Te powders was studied in situ by means of high-energy synchrotron X-ray diffraction. FeTe does not form directly from the starting elements; instead, FeTe2 forms as an intermediate product. During a 2 °C/min heating ramp, Te first reacts...

  8. Pulsed electron beam generation with fast repetitive double pulse system

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Surender Kumar; Deb, Pankaj; Shyam, Anurag, E-mail: surender80@gmail.com [Energetics and Electromagnetics Division, Bhabha Atomic Research Centre, Visakhapatnam (India); Sharma, Archana [Accelerator and Pulse Power Division, Bhabha Atomic Research Centre, Mumbai (India)

    2014-07-01

    Longer duration high voltage pulse (∼ 100 kV, 260 ns) is generated and reported using helical pulse forming line in compact geometry. The transmission line characteristics of the helical pulse forming line are also used to develop fast repetition double pulse system with very short inter pulse interval. It overcomes the limitations caused due to circuit parameters, power supplies and load characteristics for fast repetitive high voltage pulse generation. The high voltage double pulse of 100 kV, 100 ns with an inter pulse repetition interval of 30 ns is applied across the vacuum field emission diode for pulsed electron beam generation. The electron beam is generated from cathode material by application of negative high voltage (> 100 kV) across the diode by explosive electron emission process. The vacuum field emission diode is made of 40 mm diameter graphite cathode and SS mesh anode. The anode cathode gap was 6 mm and the drift tube diameter was 10 cm. The initial experimental results of pulsed electron beam generation with fast repetitive double pulse system are reported and discussed. (author)

  9. Designing Diameter-Modulated Heterostructure Nanowires of PbTe/Te by Controlled Dewetting.

    Science.gov (United States)

    Kumar, Abinash; Kundu, Subhajit; Samantaray, Debadarshini; Kundu, Paromita; Zanaga, Daniele; Bals, Sara; Ravishankar, N

    2017-12-13

    Heterostructures consisting of semiconductors with controlled morphology and interfaces find applications in many fields. A range of axial, radial, and diameter-modulated nanostructures have been synthesized primarily using vapor phase methods. Here, we present a simple wet chemical routine to synthesize heterostructures of PbTe/Te using Te nanowires as templates. A morphology evolution study for the formation of these heterostructures has been performed. On the basis of these control experiments, a pathway for the formation of these nanostructures is proposed. Reduction of a Pb precursor to Pb on Te nanowire templates followed by interdiffusion of Pb/Te leads to the formation of a thin shell of PbTe on the Te wires. Controlled dewetting of the thin shell leads to the formation of cube-shaped PbTe that is periodically arranged on the Te wires. Using control experiments, we show that different reactions parameters like rate of addition of the reducing agent, concentration of Pb precursor and thickness of initial Te nanowire play a critical role in controlling the spacing between the PbTe cubes on the Te wires. Using simple surface energy arguments, we propose a mechanism for the formation of the hybrid. The principles presented are general and can be exploited for the synthesis of other nanoscale heterostructures.

  10. Bacon, Lettuce and Tomato: een strategie om leerlingen te helpen hun antwoorden op examenvragen te verbeteren

    NARCIS (Netherlands)

    Kneppers, L.

    2014-01-01

    In Tutor2u las ik dat in een workshop een strategie was besproken om leerlingen te helpen hun examenantwoorden vollediger en juister te formuleren. De strategie heet in Groot Brittannië BLT, voor leerlingen daar gemakkelijk te onthouden vanwege de populaire Bacon, Lettuce en Tomato sandwich.

  11. Thermal analysis of an indirectly heat pulsed non-volatile phase change material microwave switch

    International Nuclear Information System (INIS)

    Young, Robert M.; El-Hinnawy, Nabil; Borodulin, Pavel; Wagner, Brian P.; King, Matthew R.; Jones, Evan B.; Howell, Robert S.; Lee, Michael J.

    2014-01-01

    We show the finite element simulation of the melt/quench process in a phase change material (GeTe, germanium telluride) used for a radio frequency switch. The device is thermally activated by an independent NiCrSi (nickel chrome silicon) thin film heating element beneath a dielectric separating it electrically from the phase change layer. A comparison is made between the predicted and experimental minimum power to amorphize (MPA) for various thermal pulse powers and pulse time lengths. By including both the specific heat and latent heat of fusion for GeTe, we find that the MPA and the minimum power to crystallize follow the form of a hyperbola on the power time effect plot. We also find that the simulated time at which the entire center GeTe layer achieves melting accurately matches the MPA curve for pulse durations ranging from 75–1500 ns and pulse powers from 1.6–4 W

  12. Thermal analysis of an indirectly heat pulsed non-volatile phase change material microwave switch

    Energy Technology Data Exchange (ETDEWEB)

    Young, Robert M., E-mail: rm.young@ngc.com; El-Hinnawy, Nabil; Borodulin, Pavel; Wagner, Brian P.; King, Matthew R.; Jones, Evan B.; Howell, Robert S.; Lee, Michael J. [Northrop Grumman Corp., Electronic Systems, P.O. Box 1521, Baltimore, Maryland 21203 (United States)

    2014-08-07

    We show the finite element simulation of the melt/quench process in a phase change material (GeTe, germanium telluride) used for a radio frequency switch. The device is thermally activated by an independent NiCrSi (nickel chrome silicon) thin film heating element beneath a dielectric separating it electrically from the phase change layer. A comparison is made between the predicted and experimental minimum power to amorphize (MPA) for various thermal pulse powers and pulse time lengths. By including both the specific heat and latent heat of fusion for GeTe, we find that the MPA and the minimum power to crystallize follow the form of a hyperbola on the power time effect plot. We also find that the simulated time at which the entire center GeTe layer achieves melting accurately matches the MPA curve for pulse durations ranging from 75–1500 ns and pulse powers from 1.6–4 W.

  13. Electronic structures and stability of Ni/Bi2Te3 and Co/Bi2Te3 interfaces

    KAUST Repository

    Xiong, Ka; Wang, Weichao; Alshareef, Husam N.; Gupta, Rahul P.; White, John B.; Gnade, Bruce E.; Cho, Kyeongjae

    2010-01-01

    We investigate the electronic structures and stability for Ni/Bi 2Te3, NiTe/Bi2Te3, Co/Bi 2Te3 and CoTe2/Bi2Te3 interfaces by first-principles calculations. It is found that the surface termination strongly affects the band alignment. Ni and Co are found to form Ohmic contacts to Bi2Te3. The interface formation energy for Co/Bi2Te3 interfaces is much lower than that of Ni/Bi2Te3 interfaces. Furthermore, we found that NiTe on Bi2Te3 is more stable than Ni, while the formation energies for Co and CoTe2 on Bi2Te3 are comparable. © 2010 IOP Publishing Ltd.

  14. Electronic structures and stability of Ni/Bi2Te3 and Co/Bi2Te3 interfaces

    International Nuclear Information System (INIS)

    Xiong Ka; Wang Weichao; Alshareef, Husam N; Gupta, Rahul P; Gnade, Bruce E; Cho, Kyeongjae; White, John B

    2010-01-01

    We investigate the electronic structures and stability for Ni/Bi 2 Te 3 , NiTe/Bi 2 Te 3 , Co/Bi 2 Te 3 and CoTe 2 /Bi 2 Te 3 interfaces by first-principles calculations. It is found that the surface termination strongly affects the band alignment. Ni and Co are found to form Ohmic contacts to Bi 2 Te 3 . The interface formation energy for Co/Bi 2 Te 3 interfaces is much lower than that of Ni/Bi 2 Te 3 interfaces. Furthermore, we found that NiTe on Bi 2 Te 3 is more stable than Ni, while the formation energies for Co and CoTe 2 on Bi 2 Te 3 are comparable.

  15. Electronic structures and stability of Ni/Bi2Te3 and Co/Bi2Te3 interfaces

    KAUST Repository

    Xiong, Ka

    2010-03-04

    We investigate the electronic structures and stability for Ni/Bi 2Te3, NiTe/Bi2Te3, Co/Bi 2Te3 and CoTe2/Bi2Te3 interfaces by first-principles calculations. It is found that the surface termination strongly affects the band alignment. Ni and Co are found to form Ohmic contacts to Bi2Te3. The interface formation energy for Co/Bi2Te3 interfaces is much lower than that of Ni/Bi2Te3 interfaces. Furthermore, we found that NiTe on Bi2Te3 is more stable than Ni, while the formation energies for Co and CoTe2 on Bi2Te3 are comparable. © 2010 IOP Publishing Ltd.

  16. Pulsed current generator

    International Nuclear Information System (INIS)

    Semenov, V.D.; Furman, Eh.G.

    1974-01-01

    The paper describes a current pulse generator with an auxiliary network consisting of a choke and diode in series designed to enlarge the range of pulse frequency control. One output of the network is connected to an adjustable valve cathode and via antoher auxiliary condenser to the point where the cathode of the main key unit is joined to the start of the magnetizing coil. A second output is connected to the anode of another adjustable valve and via another auxiliary condenser to the point where the anode of the other main key unit is joined to the end of the magnetizing coil. The generator can be used to excite the electromagnets of charged particle accelerators or in devices designed to produce magnetic fields. (author)

  17. Fast pulse amplifier

    International Nuclear Information System (INIS)

    Lepetit, J.; Poussier, E.

    1984-01-01

    This amplifier comprises an inverter transformer, the primary circuit of which receives a pulse and the secondary circuit of which is connected to several amplifying elements in parallel. The inverter transformer is made of coaxial cable segments winded around a magnetic torus; the cable cores connected in series constitute the primary circuit and the braiding of cables, connected in parallel, are the secondary circuit. The transformer comprises, besides, delay lines in series with each braiding of the secondary circuit, these ones are such that pulses issued from each braiding arrive together to the secondary circuit connectors. This invention applies, noticeably in the case of a high voltage amplifier, to the control of deflection blocks of particles used in medicine or in particle accelerators [fr

  18. Linear pulse amplifier

    International Nuclear Information System (INIS)

    Tjutju, R.L.

    1977-01-01

    Pulse amplifier is standard significant part of spectrometer. Apart from other type of amplification, it's a combination of amplification and pulse shaping. Because of its special purpose the device should fulfill the following : High resolution is desired to gain a high yield comparable to its actual state of condition. High signal to noise is desired to nhν resolution. High linearity to facilitate calibration. A good overload recovery, in order to the device will capable of analizing a low energy radiation which appear joinly on the high energy fields. Other expections of the device are its economical and practical use its extentive application. For that reason it's built on a standard NIM principle. Taking also into account the above mentioned considerations. High quality component parts are used throughout, while its availability in the domestic market is secured. (author)

  19. Pulsed fusion reactors

    International Nuclear Information System (INIS)

    1975-01-01

    This summer school specialized in examining specific fusion center systems. Papers on scientific feasibility are first presented: confinement of high-beta plasma, liners, plasma focus, compression and heating and the use of high power electron beams for thermonuclear reactors. As for technological feasibility, lectures were on the theta-pinch toroidal reactors, toroidal diffuse pinch, electrical engineering problems in pulsed magnetically confined reactors, neutral gas layer for heat removal, the conceptual design of a series of laser fusion power plants with ''Saturn'', implosion experiments and the problem of the targets, the high brightness lasers for plasma generation, and topping and bottoming cycles. Some problems common to pulsed reactors were examined: energy storage and transfer, thermomechanical and erosion effects in the first wall and blanket, the problems of tritium production, radiation damage and neutron activation in blankets, and the magnetic and inertial confinement

  20. Short pulse neutron generator

    Science.gov (United States)

    Elizondo-Decanini, Juan M.

    2016-08-02

    Short pulse neutron generators are described herein. In a general embodiment, the short pulse neutron generator includes a Blumlein structure. The Blumlein structure includes a first conductive plate, a second conductive plate, a third conductive plate, at least one of an inductor or a resistor, a switch, and a dielectric material. The first conductive plate is positioned relative to the second conductive plate such that a gap separates these plates. A vacuum chamber is positioned in the gap, and an ion source is positioned to emit ions in the vacuum chamber. The third conductive plate is electrically grounded, and the switch is operable to electrically connect and disconnect the second conductive plate and the third conductive plate. The at least one of the resistor or the inductor is coupled to the first conductive plate and the second conductive plate.

  1. Infrared and near infrared emission spectra of TeH and TeD

    Science.gov (United States)

    Yu, Shanshan; Shayesteh, Alireza; Fu, Dejian; Bernath, Peter F.

    2005-04-01

    The vibration-rotation emission spectra for the X2Π ground state and the near infrared emission spectra of the X2Π 1/2- X2Π 3/2 system of the TeH and TeD free radicals have been measured at high resolution using a Fourier transform spectrometer. TeH and TeD were generated in a tube furnace with a DC discharge of a flowing mixture of argon, hydrogen (or deuterium), and tellurium vapor. In the infrared region, for the X2Π 3/2 spin component we observed the 1-0, 2-1, and 3-2 vibrational bands for most of the eight isotopologues of TeH and the 1-0 and 2-1 bands for three isotopologues of TeD. For the X2Π 1/2- X2Π 3/2 transition, we observed the 0-0 and 1-1 bands for TeH and the 0-0, 1-1, and 2-2 bands for TeD. Except for a few lines, the tellurium isotopic shift was not resolved for the X2Π 1/2- X2Π 3/2 transitions of TeH and TeD. Local perturbations with Δ v = 2 between the two spin components of the X2Π state of TeH were found: X2Π 1/2, v = 0 with X2Π 3/2, v = 2; X2Π 1/2, v = 1 with X2Π 3/2, v = 3. The new data were combined with the previous data from the literature and two kinds of fits (Hund's case (a) and Hund's case (c)) were carried out for each of the 10 observed isotopologues: 130TeD, 128TeD, 126TeD, 130TeH, 128TeH, 126TeH, 125TeH, 124TeH, 123TeH, and 122TeH.

  2. Thermoelectric properties of c-GeSb{sub 0.75}Te{sub 0.5} to h-GeSbTe{sub 0.5} thin films through annealing treatment effects

    Energy Technology Data Exchange (ETDEWEB)

    Vora-ud, Athorn, E-mail: athornvora-ud@snru.ac.th [Program of Physics, Faculty of Science and Technology, Sakon Nakhon Rajabhat University, Mueang District, Sakon Nakhon 47000 (Thailand); Thermoelectrics Research Center, Research and Development Institution, Sakon Nakhon Rajabhat University, Mueang District, Sakon Nakhon 47000 (Thailand); Horprathum, Mati, E-mail: mati.horprathum@nectec.or.th [National Electronics and Computer Technology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Eiamchai, Pitak [National Electronics and Computer Technology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Muthitamongkol, Pennapa; Chayasombat, Bralee; Thanachayanont, Chanchana [National Metal and Materials Technology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Pankiew, Apirak [National Electronics and Computer Technology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Klamchuen, Annop [National Nanotechnology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Naenkieng, Daengdech; Plirdpring, Theerayuth; Harnwunggmoung, Adul [Thermoelectric and Nanotechnology Research Center, Faculty of Science and Technology, Rajamangala University of Technology Suvarnabhumi, Huntra Phranakhon, Si Ayutthaya 13000 (Thailand); Charoenphakdee, Anek [NANO-Thermoelectrics Research Center, Division of Applied Physics, Faculty of Sciences and Liberal Arts, Rajamangala University of Technology Isan, Mueng Nakorn Ratchasima 30000 Thailand (Thailand); Somkhunthot, Weerasak [Program of Physics, Faculty of Science and Technology, Loei Rajabhat University, Muang District, Loei 42000 (Thailand); and others

    2015-11-15

    Germanium–Antimony–Tellurium (Ge–Sb–Te) thin films were deposited on silicon wafers with 1-μm silicon dioxide (SiO{sub 2}/Si) by pulsed dc magnetron sputtering from a 99.99% GeSbTe target of 1:1:1 ratio at ambient temperature. The samples were annealed at 573, 623, 673, and 723 K for 3600 s in a vacuum state. The effects of the annealing treatment on phase identification, atomic composition, morphology and film thickness, carrier concentration, mobility, and Seebeck coefficient of the Ge–Sb–Te samples have been investigated by grazing-incidence X-ray diffraction, auger electron spectroscopy, field-emission scanning electron microscopy, Hall-effect measurements, and steady state method, respectively. The results demonstrated that the as-deposited Ge–Sb–Te sample was amorphous. Atomic composition of as-deposited and annealed films at 573 K and 623 K were GeSb{sub 0.75}Te{sub 0.5} while annealed films at 673 K and 723 K were GeSbTe{sub 0.5} due to Sb-rich GeSb{sub 0.75}Te{sub 0.5}. The samples annealed at 573 K and 623 K showed the crystal phases of cubic structure (c-GeSb{sub 0.75}Te{sub 0.5}) into hexagonal structure (h-GeSbTe{sub 0.5}) after annealing at 673 K and 723 K. The study demonstrated the insulating condition from the as-deposited GeSbTe film, and the changes towards the thermoelectric properties from the annealing treatments. The GeSbTe films annealed at 673 K yielded excellent thermoelectric properties with the electrical resistivity, Seebeck coefficient, and power factor at approximately 1.45 × 10{sup −5} Ωm, 71.07 μV K{sup −1}, and 3.48 × 10{sup −4} W m{sup −1} K{sup −2}, respectively. - Highlights: • GeSbTe thin films were successfully sputtered for thermoelectric properties. • GeSbTe films were examined among physical, electrical and thermoelectric properties. • Thermoelectric properties were discussed based on composition of the films.

  3. Pulsed rf operation analysis

    International Nuclear Information System (INIS)

    Puglisi, M.; Cornacchia, M.

    1981-01-01

    The need for a very low final amplifier output impedance, always associated with class A operation, requires a very large power waste in the final tube. The recently suggested pulsed rf operation, while saving a large amount of power, increases the inherent final amplifier non linearity. A method is presented for avoiding the large signal non linear analysis and it is shown how each component of the beam induced voltage depends upon all the beam harmonics via some coupling coefficients which are evaluated

  4. PULSE Pilot Certification Results

    Directory of Open Access Journals (Sweden)

    Pamela Pape-Lindstrom

    2015-08-01

    Full Text Available The pilot certification process is an ambitious, nationwide endeavor designed to motivate important changes in life sciences education that are in line with the recommendations of the 2011 Vision and Change Report: A Call to Action (American Association for the Advancement of Science [AAAS], 2011.  It is the goal of the certification process to acknowledge departments that have progressed towards full implementation of the tenets of Vision and Change and to motivate departments that have not begun to adopt the recommendations to consider doing so.  More than 70 life science departments applied to be part of the pilot certification process, funded by a National Science Foundation grant, and eight were selected based on initial evidence of transformed and innovative educational practices.  The programs chosen represent a wide variety of schools, including two-year colleges, liberal-arts institutions, regional comprehensive colleges, research universities and minority serving institutions.  Outcomes from this pilot were released June 1, 2015 (www.pulsecommunity.org, with all eight programs being recognized as having progressed along a continuum of change.  Five levels of achievement were defined as PULSE Pilot Progression Levels.  Of the eight departments in the pilot, one achieved “PULSE Progression Level III: Accomplished”.  Six departments achieved “PULSE Progression Level II: Developing” and one pilot department achieved “PULSE Progression Level I: Beginning”.  All of the schools have made significant movement towards the recommendations of Vision and Change relative to a traditional life sciences curriculum.  Overall, the response from the eight pilot schools has been positive. 

  5. STUCTURE OF PULSED BED

    Directory of Open Access Journals (Sweden)

    I. A. Bokun

    2014-01-01

    Full Text Available The structure of pulsed layer is proposed which can be suggested as a state of particulates that is blown by intermittent gas flow with speed which has the force to start material moving. Layer during one cycle is in a suspension, falling down and immobile state resulting in changes of particles arrangement as well as ways of gas flowing through layer. Moreover, it allows carrying out effective interphase heat exchange even adamant real granulation.The process of formation of impact flows is considered aw well as their influence on formation of air bubbles in pulsed layer. At startup of air blast the balance between the force of hydro-dynamic resistance is broken, on one side, and forces of gravity, particles inertia and their links with walls on the other side. The layer is transferred in the state of pulsed pseudo-fluidization, and presents gas-disperse mixture, inside of which impulse of pressure increasing is spreading to all sides as pressure waves (compression. These waves are the sources of impact flows’ formation, the force of which is two times more than during the stationary flow.The waves of pressure are divided into weak and strong ones depending on movement velocity within gas-disperse system. Weak waves are moving with a sound speed and strong ones in active phase of pulsed layer are moving over the speed of sound limit within gas-disperse system. The peculiarity of strong wave is that parameters of system (pressure, density and others are changing in discrete steps.The article describes the regime of layer’s falling down in the passive stage of cycle, which begins after finishing of gas impulse action. And suspension layer of moving up granular material is transferred in the state of falling resulting in change of the layer structure.

  6. Downhole pulse radar

    Science.gov (United States)

    Chang, Hsi-Tien

    1987-09-28

    A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole. 7 figs.

  7. Pulsed polarimetry progress on the LANL MSX magnetized shock experiment

    Science.gov (United States)

    Smith, R. J.; Intrator, T. P.; Weber, T. E.; Hutchinson, T. M.; Boguski, J. C.

    2013-10-01

    The UW pulsed polarimeter is a Lidar Thomson scattering diagnostic that can also provide measurements of the internal distribution of B| | as well as ne and Te for Magnetized High Energy Density targets with cm resolution. Scattering has now been observed in MSX and mirror issues that interrupted the last campaign have been corrected. Subsidiary diagnostics are being developed along side to aid in calibration. Fiber optic pulsed polarimetry is also being explored as both measurements can be performed simultaneously with the one instrument. The fiber sensing would allow measurements of modest fields using an internal cladded fiber. Progress in these directions will be presented. This work is supported by DOE Office of Fusion Energy Sciences.

  8. Ti-Sb-Te alloy: a candidate for fast and long-life phase-change memory.

    Science.gov (United States)

    Xia, Mengjiao; Zhu, Min; Wang, Yuchan; Song, Zhitang; Rao, Feng; Wu, Liangcai; Cheng, Yan; Song, Sannian

    2015-04-15

    Phase-change memory (PCM) has great potential for numerous attractive applications on the premise of its high-device performances, which still need to be improved by employing a material with good overall phase-change properties. In respect to fast speed and high endurance, the Ti-Sb-Te alloy seems to be a promising candidate. Here, Ti-doped Sb2Te3 (TST) materials with different Ti concentrations have been systematically studied with the goal of finding the most suitable composition for PCM applications. The thermal stability of TST is improved dramatically with increasing Ti content. The small density change of T0.32Sb2Te3 (2.24%), further reduced to 1.37% for T0.56Sb2Te3, would greatly avoid the voids generated at phase-change layer/electrode interface in a PCM device. Meanwhile, the exponentially diminished grain size (from ∼200 nm to ∼12 nm), resulting from doping more and more Ti, enhances the adhesion between phase-change film and substrate. Tests of TST-based PCM cells have demonstrated a fast switching rate of ∼10 ns. Furthermore, because of the lower thermal conductivities of TST materials, compared with Sb2Te3-based PCM cells, T0.32Sb2Te3-based ones exhibit lower required pulse voltages for Reset operation, which largely decreases by ∼50% for T0.43Sb2Te3-based ones. Nevertheless, the operation voltages for T0.56Sb2Te3-based cells dramatically increase, which may be due to the phase separation after doping excessive Ti. Finally, considering the decreased resistance ratio, TixSb2Te3 alloy with x around 0.43 is proved to be a highly promising candidate for fast and long-life PCM applications.

  9. Pulse radiolysis of gases

    International Nuclear Information System (INIS)

    Nielsen, O.J.

    1984-04-01

    The pulse radiolysis equipment and technique are described and its relevance to atmospheric chemistry is discussed. Pulse radiolysis of a number of different chemical systems have been used to check the validity of the proposed mechanisms: 1) The hydrogen atom yield in the pulse radiolysis of H 2 was measured by four independent calibration techniques, using reactions of H with O 2 , C1NO, and HI. The H atom yield was compared with O 2 yields in pure O 2 and in O 2 /SF 6 mixtures which lead to a value G(H) = 17.6. The rate constants at room temperature of several reactions were determined. 2) OH radical reactions with tetraalkyllead at room temperature and with ethane, methane, and a series of C1- and F-substituted methanes at 300-400 K were studied. Arrhenius parameters, A and Esub(a), were determined for several reactions. The lifetime of Pb(CH 3 ) 4 and Pb(C 2 H 5 ) 4 in ambient air is estimated. CF 2 C1 2 was found to be a very efficient third body, M, in the reaction OH + OH + M arrow H 2 O 2 + M. 3) In the H 2 S systems the HS extinction coefficient at 3242 AA was determined to 9.5 x 10 2 cm -1 mol -1 . Four rate constants at room temperature were determined. (author)

  10. Cd-Te-In oxide thin films as possible transparent buffer layer in CdTe based solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Castro-Rodriguez, R; Camacho, J M; Pena, J L [Applied Physics Department, CINVESTAV-IPN Merida, C.P. 97310, Merida, Yucatan (Mexico); Martel, A; Mendez-Gamboa, J, E-mail: romano@mda.cinvestav.m [Facultad de Ingenieria, Universidad Autonoma de Yucatan. AP 150 Cordemex, 97310 Merida, Yucatan (Mexico)

    2009-05-01

    Cd-Te-In-oxide thin films were grown by Pulsed Laser Deposition (PLD) technique using CdTe powder embedded in a matrix of indium metallic as target. The films were deposited at different oxygen pressures (P{sub o2}) from 15 to 50 mTorr at substrate temperature of 420{sup 0}C. Sheet resistance (R{sub sheet}) and transmission spectrum were measured as a function of P{sub o2}. From measurements of optical transmission, the Photonic Flux Density (PFD) spectrum were obtained and the integral of these PFD for each film were evaluated between energy range of 1.5 eV and 2.4 eV for obtain the amount of photons that can be transferred across the film in this range of solar energy spectrum. These values were evaluated over the R{sub sheet} to be used as a figure of merit. The best choice in our conditions was the films with P{sub o2} =28.5 mTorr, where the figure of merit reaches the maximum value.

  11. Petawatt pulsed-power accelerator

    Science.gov (United States)

    Stygar, William A.; Cuneo, Michael E.; Headley, Daniel I.; Ives, Harry C.; Ives, legal representative; Berry Cottrell; Leeper, Ramon J.; Mazarakis, Michael G.; Olson, Craig L.; Porter, John L.; Wagoner; Tim C.

    2010-03-16

    A petawatt pulsed-power accelerator can be driven by various types of electrical-pulse generators, including conventional Marx generators and linear-transformer drivers. The pulsed-power accelerator can be configured to drive an electrical load from one- or two-sides. Various types of loads can be driven; for example, the accelerator can be used to drive a high-current z-pinch load. When driven by slow-pulse generators (e.g., conventional Marx generators), the accelerator comprises an oil section comprising at least one pulse-generator level having a plurality of pulse generators; a water section comprising a pulse-forming circuit for each pulse generator and a level of monolithic triplate radial-transmission-line impedance transformers, that have variable impedance profiles, for each pulse-generator level; and a vacuum section comprising triplate magnetically insulated transmission lines that feed an electrical load. When driven by LTD generators or other fast-pulse generators, the need for the pulse-forming circuits in the water section can be eliminated.

  12. Foundations of pulsed power technology

    CERN Document Server

    Lehr, Janet

    2018-01-01

    Pulsed power technologies could be an answer to many cutting-edge applications. The challenge is in how to develop this high-power/high-energy technology to fit current market demands of low-energy consuming applications. This book provides a comprehensive look at pulsed power technology and shows how it can be improved upon for the world of today and tomorrow. Foundations of Pulsed Power Technology focuses on the design and construction of the building blocks as well as their optimum assembly for synergetic high performance of the overall pulsed power system. Filled with numerous design examples throughout, the book offers chapter coverage on various subjects such as: Marx generators and Marx-like circuits; pulse transformers; pulse-forming lines; closing switches; opening switches; multi-gigawatt to multi-terawatt systems; energy storage in capacitor banks; electrical breakdown in gases; electrical breakdown in solids, liquids and vacuum; pulsed voltage and current measurements; electromagnetic interferen...

  13. High mobility 2D electron gas in CdTe/CdMgTe heterostructures

    International Nuclear Information System (INIS)

    Karczewski, G.; Jaroszynski, J.; Kurowski, M.; Barcz, A.; Wojtowicz, T.; Kossut, J.

    1997-01-01

    We report on iodine doping of molecular beam epitaxy (MBE)-grown Cd(Mn)Te quasi-bulk films and modulation-doped CdTe/Cd 1-y Mg y Te two-dimensional (2D) single quantum well structures. Modulation doping with iodine of CdTe/Cd 1-y Mg y Te structures resulted in fabrication of a 2D electron gas with mobility exceeding 10 5 cm 2 /(Vs). This is the highest mobility reported in wide-gap II-VI materials

  14. Experimental Study of RF Pulsed Heating on Oxygen Free Electronic Copper

    Energy Technology Data Exchange (ETDEWEB)

    Pritzkau, David P.

    2003-02-10

    When the thermal stresses induced by RF pulsed heating are larger than the elastic limit, microcracks and surface roughening will occur due to cyclic fatigue. Therefore, pulsed heating limits the maximum surface magnetic field and through it the maximum achievable accelerating gradient. An experiment using circularly cylindrical cavities operating in the TE{sub 011} mode at a resonant frequency of 11.424 GHz was designed to study pulsed heating on Oxygen Free Electronic (OFE) copper. An X-band klystron delivered up to 10 MW to the cavities in 1.5 {micro}s pulses at 60 Hz repetition rate. One run was executed at a temperature rise of 120 K for 56 x 10{sup 6} pulses. Cracks at grain boundaries, slip bands and cracks associated with these slip bands were observed. The second run consisted of 86 x 10{sup 6} pulses with a temperature rise of 82 K, and cracks at grain boundaries and slip bands were seen. Additional information can be derived from the power-coupling iris, and we conclude that a pulsed temperature rise of 250 K for several million pulses leads to destruction of copper. These results can be applied to any mode of any OFE copper cavity.

  15. Analysis of CdS/CdTe devices incorporating a ZnTe:Cu/Ti Contact

    International Nuclear Information System (INIS)

    Gessert, T.A.; Asher, S.; Johnston, S.; Young, M.; Dippo, P.; Corwine, C.

    2007-01-01

    High-performance CdS/CdTe photovoltaic devices can be produced using a ZnTe:Cu/Ti back contact deposited onto the CdTe layer. We observe that prolonged exposure of the ZnTe:Cu and Ti sputtering targets to an oxygen-containing plasma significantly reduces device open-circuit voltage and fill factor. High-resolution compositional analysis of these devices reveals that Cu concentration in the CdTe and CdS layers is lower for devices with poor performance. Capacitance-voltage analysis and related numerical simulations indicate that the net acceptor concentration in the CdTe is also lower for devices with poor performance. Photoluminescence analyses of the junction region reveal that the intensity of a luminescent peak associated with a defect complex involving interstitial Cu (Cu i ) and oxygen on Te (O Te ) is reduced in devices with poor performance. Combined with thermodynamic considerations, these results suggest that oxygen incorporation into the ZnTe:Cu sputtering target reduces the ability of sputtered ZnTe:Cu film to diffuse Cu into the CdTe

  16. Self-Catalyzed CdTe Wires

    Directory of Open Access Journals (Sweden)

    Tom Baines

    2018-04-01

    Full Text Available CdTe wires have been fabricated via a catalyst free method using the industrially scalable physical vapor deposition technique close space sublimation. Wire growth was shown to be highly dependent on surface roughness and deposition pressure, with only low roughness surfaces being capable of producing wires. Growth of wires is highly (111 oriented and is inferred to occur via a vapor-solid-solid growth mechanism, wherein a CdTe seed particle acts to template the growth. Such seed particles are visible as wire caps and have been characterized via energy dispersive X-ray analysis to establish they are single phase CdTe, hence validating the self-catalysation route. Cathodoluminescence analysis demonstrates that CdTe wires exhibited a much lower level of recombination when compared to a planar CdTe film, which is highly beneficial for semiconductor applications.

  17. Photonic-band-gap gyrotron amplifier with picosecond pulses

    Science.gov (United States)

    Nanni, Emilio A.; Jawla, Sudheer; Lewis, Samantha M.; Shapiro, Michael A.; Temkin, Richard J.

    2017-12-01

    We report the amplification of 250 GHz pulses as short as 260 ps without observation of pulse broadening using a photonic-band-gap circuit gyrotron traveling-wave-amplifier. The gyrotron amplifier operates with a device gain of 38 dB and an instantaneous bandwidth of 8 GHz. The operational bandwidth of the amplifier can be tuned over 16 GHz by adjusting the operating voltage of the electron beam and the magnetic field. The amplifier uses a 30 cm long photonic-band-gap interaction circuit to confine the desired TE03-like operating mode while suppressing lower order modes which can result in undesired oscillations. The circuit gain is >55 dB for a beam voltage of 23 kV and a current of 700 mA. These results demonstrate the wide bandwidths and a high gain achievable with gyrotron amplifiers. The amplification of picosecond pulses of variable lengths, 260-800 ps, shows good agreement with the theory using the coupled dispersion relation and the gain-spectrum of the amplifier as measured with quasi-CW input pulses.

  18. Development of an advanced Two-Micron triple-pulse IPDA lidar for carbon dioxide and water vapor measurements

    Science.gov (United States)

    Petros, Mulugeta; Refaat, Tamer F.; Singh, Upendra N.; Yu, Jirong; Antill, Charles; Remus, Ruben; Taylor, Bryant D.; Wong, Teh-Hwa; Reithmaier, Karl; Lee, Jane; Ismail, Syed; Davis, Kenneth J.

    2018-04-01

    An advanced airborne triple-pulse 2-μm integrated path differential absorption (IPDA) lidar is under development at NASA Langley Research Center that targets both carbon dioxide (CO2) and water vapor (H2O) measurements simultaneously and independently. This lidar is an upgrade to the successfully demonstrated CO2 2-μm double-pulse IPDA. Upgrades include high-energy, highrepetition rate 2-μm triple-pulse laser transmitter, innovative wavelength control and advanced HgCdTe (MCT) electron-initiated avalanche photodiode detection system. Ground testing and airborne validation plans are presented.

  19. Magnicon development to power TeV colliders. Final report, 16 May 1991--14 May 1994

    International Nuclear Information System (INIS)

    Gold, S.H.; Manheimer, W.M.; Fliflet, A.

    1997-01-01

    The goal of this program was the development of a high power frequency-doubling magnicon amplifier at 11.4 GHz. The magnicon is an advanced open-quotes scanning-beamclose quotes microwave amplifier tube for use in powering future high gradient linear accelerators, such as the proposed TeV linear collider known as the Next Linear Collider (NLC). The rf source for the NLC must provide a power of 500 MW to 1 GW per tube in a 200 nsec pulse at a frequency in the range of 10-20 GHz. The required power can either be generated directly in 200 nsec pulses, or generated at longer pulse lengths (e.g., 1-2 μsec) and then pulse-compressed. Because the average power required by the NLC is so large, source efficiency is a crucial consideration

  20. Development of the pulse transformer for NLC klystron pulse modulator

    International Nuclear Information System (INIS)

    Akemoto, M.; Gold, S.; Koontz, R.; Krasnykh, A.

    1997-05-01

    We have studied a conventional pulse transformer for the NLC klystron pulse modulator. The transformer has been analyzed using a simplified lumped circuit model. It is found that a fast rise time requires low leakage inductance and low distributed capacitance and can be realized by reducing the number of secondary turns, but it produces larger pulse droop and core size. After making a tradeoff among these parameters carefully, a conventional pulse transformer with a rise time of 250ns and pulse droop of 3.6% has been designed and built. The transmission characteristics and pulse time-response were measured. The data were compared with the model. The agreement with the model was good when the measured values were used in the model simulation. The results of the high voltage tests are also presented

  1. Pulse transformer R and D for NLC klystron pulse modulator

    International Nuclear Information System (INIS)

    Akemoto, M.; Gold, S.; Krasnykh, A.; Koontz, R.

    1997-07-01

    The authors have studied a conventional pulse transformer for the NLC klystron pulse modulator. The transformer has been analyzed using a simplified lumped circuit model. It is found that a fast rise time requires low leakage inductance and low distributed capacitance and can be realized by reducing the number of secondary turns, but it produces larger pulse droop and requires a larger core size. After making a tradeoff among these parameters carefully, a conventional pulse transformer with a rise time of 250ns and a pulse droop of 3.6% has been designed and built. The transmission characteristics and pulse time-response were measured. The data were compared with the model. The agreement with the model was good when the measured values were used in the model simulation. The results of the high voltage tests using a klystron load are also presented

  2. A thermodynamic stability of bulk and epitaxial CdHgTe, ZnHgTe and MnHgTe solid solutions

    International Nuclear Information System (INIS)

    Dejbuk, V.G.; Dremlyuzhenko, S.G.; Ostapov, S.Eh.

    2005-01-01

    A thermodynamics of Cd 1-x Hg x Te, Zn x Hg 1-x Te and Mg x Hg 1-x Te alloys has been investigated for a delta-lattice parameter model. The phase diagrams obtained show the stability of Cd 1-x Hg x Te, Zn x Hg 1-x Te in the whole range of compositions, alongside with a miscibility gap for Mn x Hg 1-x Te being of 0.35 x Hg 1-x Te/CdTe and Mn x Hg 1-x Te/Cd 0.96 Zn 0.04 Te epitaxial films result in lowering critical temperatures and narrowing the miscibility gap [ru

  3. Single-Photon-Sensitive HgCdTe Avalanche Photodiode Detector

    Science.gov (United States)

    Huntington, Andrew

    2013-01-01

    The purpose of this program was to develop single-photon-sensitive short-wavelength infrared (SWIR) and mid-wavelength infrared (MWIR) avalanche photodiode (APD) receivers based on linear-mode HgCdTe APDs, for application by NASA in light detection and ranging (lidar) sensors. Linear-mode photon-counting APDs are desired for lidar because they have a shorter pixel dead time than Geiger APDs, and can detect sequential pulse returns from multiple objects that are closely spaced in range. Linear-mode APDs can also measure photon number, which Geiger APDs cannot, adding an extra dimension to lidar scene data for multi-photon returns. High-gain APDs with low multiplication noise are required for efficient linear-mode detection of single photons because of APD gain statistics -- a low-excess-noise APD will generate detectible current pulses from single photon input at a much higher rate of occurrence than will a noisy APD operated at the same average gain. MWIR and LWIR electron-avalanche HgCdTe APDs have been shown to operate in linear mode at high average avalanche gain (M > 1000) without excess multiplication noise (F = 1), and are therefore very good candidates for linear-mode photon counting. However, detectors fashioned from these narrow-bandgap alloys require aggressive cooling to control thermal dark current. Wider-bandgap SWIR HgCdTe APDs were investigated in this program as a strategy to reduce detector cooling requirements.

  4. Pixelized M-pi-n CdTe detector coupled to Medipix2 readout chip

    CERN Document Server

    Kalliopuska, J; Penttila, R; Andersson, H; Nenonen, S; Gadda, A; Pohjonen, H; Vanttajac, I; Laaksoc, P; Likonen, J

    2011-01-01

    We have realized a simple method for patterning an M-pi-n CdTe diode with a deeply diffused pn-junction, such as indium anode on CdTe. The method relies on removing the semiconductor material on the anode-side of the diode until the physical junction has been reached. The pixelization of the p-type CdTe diode with an indium anode has been demonstrated by patterning perpendicular trenches with a high precision diamond blade and pulsed laser. Pixelization or microstrip pattering can be done on both sides of the diode, also on the cathode-side to realize double sided detector configuration. The article compares the patterning quality of the diamond blade process, pulsed pico-second and femto-second lasers processes. Leakage currents and inter-strip resistance have been measured and are used as the basis of the comparison. Secondary ion mass spectrometry (SIMS) characterization has been done for a diode to define the pn-junction depth and to see the effect of the thermal loads of the flip-chip bonding process. Th...

  5. Energy dispersive CdTe and CdZnTe detectors for spectral clinical CT and NDT applications

    Energy Technology Data Exchange (ETDEWEB)

    Barber, W.C., E-mail: william.barber@dxray.com [DxRay, Inc., Northridge, CA (United States); Interon AS, Asker (Norway); Wessel, J.C. [DxRay, Inc., Northridge, CA (United States); Interon AS, Asker (Norway); Nygard, E. [Interon AS, Asker (Norway); Iwanczyk, J.S. [DxRay, Inc., Northridge, CA (United States)

    2015-06-01

    -flux ASICs with a two dimensional (2D) array of inputs for readout from the sensors. The sensors are guard ring free and have a 2D array of pixels and can be tiled in 2D while preserving pixel pitch. The 2D ASICs have four energy bins with a linear energy response across sufficient dynamic range for clinical CT and some NDT applications. The ASICs can also be tiled in 2D and are designed to fit within the active area of the sensors. We have measured several important performance parameters including: the output count rate (OCR) in excess of 20 million counts per second per square mm with a minimum loss of counts due to pulse pile-up, an energy resolution of 7 keV full width at half-maximum (FWHM) across the entire dynamic range, and a noise floor about 20 keV. This is achieved by directly interconnecting the ASIC inputs to the pixels of the CdZnTe sensors incurring very little input capacitance to the ASICs. We present measurements of the performance of the CdTe and CdZnTe sensors including the OCR, FWHM energy resolution, noise floor, as well as the temporal stability and uniformity under the rapidly varying high flux expected in CT and NDT applications.

  6. Coiled transmission line pulse generators

    Science.gov (United States)

    McDonald, Kenneth Fox

    2010-11-09

    Methods and apparatus are provided for fabricating and constructing solid dielectric "Coiled Transmission Line" pulse generators in radial or axial coiled geometries. The pour and cure fabrication process enables a wide variety of geometries and form factors. The volume between the conductors is filled with liquid blends of monomers, polymers, oligomers, and/or cross-linkers and dielectric powders; and then cured to form high field strength and high dielectric constant solid dielectric transmission lines that intrinsically produce ideal rectangular high voltage pulses when charged and switched into matched impedance loads. Voltage levels may be increased by Marx and/or Blumlein principles incorporating spark gap or, preferentially, solid state switches (such as optically triggered thyristors) which produce reliable, high repetition rate operation. Moreover, these Marxed pulse generators can be DC charged and do not require additional pulse forming circuitry, pulse forming lines, transformers, or an a high voltage spark gap output switch. The apparatus accommodates a wide range of voltages, impedances, pulse durations, pulse repetition rates, and duty cycles. The resulting mobile or flight platform friendly cylindrical geometric configuration is much more compact, light-weight, and robust than conventional linear geometries, or pulse generators constructed from conventional components. Installing additional circuitry may accommodate optional pulse shape improvements. The Coiled Transmission Lines can also be connected in parallel to decrease the impedance, or in series to increase the pulse length.

  7. High current transistor pulse generator

    International Nuclear Information System (INIS)

    Nesterov, V.; Cassel, R.

    1991-05-01

    A solid state pulse generator capable of delivering high current trapezoidally shaped pulses into an inductive load has been developed at SLAC. Energy stored in the capacitor bank of the pulse generator is switched to the load through a pair of Darlington transistors. A combination of diodes and Darlington transistors is used to obtain trapezoidal or triangular shaped current pulses into an inductive load and to recover the remaining energy in the same capacitor bank without reversing capacitor voltage. The transistors work in the switch mode, and the power losses are low. The rack mounted pulse generators presently used at SLAC contain a 660 microfarad storage capacitor bank and can deliver 400 amps at 800 volts into inductive loads up to 3 mH. The pulse generators are used in several different power systems, including pulse to pulse bipolar power supplies and in application with current pulses distributed into different inductive loads. The current amplitude and discharge time are controlled by the central computer system through a specially developed multichannel controller. Several years of operation with the pulse generators have proven their consistent performance and reliability. 8 figs

  8. Versatile pulse programmer for pulsed nuclear magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Adduci, D.J.

    1979-05-01

    A description of the sequence of events and the decisions leading to the design of a versatile pulse programmer for pulsed NMR are presented. Background and application information is discussed in order that the reader might better understand the role of the pulse programmer in a NMR spectrometer. Various other design approaches are presented as a basis for comparison. Specifications for this design are proposed, the hardware implementation of the specifications is discussed, and the software operating system is presented

  9. Versatile pulse programmer for pulsed nuclear magnetic resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Adduci, D.J.

    1979-05-01

    A description of the sequence of events and the decisions leading to the design of a versatile pulse programmer for pulsed NMR are presented. Background and application information is discussed in order that the reader might better understand the role of the pulse programmer in a NMR spectrometer. Various other design approaches are presented as a basis for comparison. Specifications for this design are proposed, the hardware implementation of the specifications is discussed, and the software operating system is presented.

  10. Pulsed power for fusion

    International Nuclear Information System (INIS)

    Martin, T.H.

    1976-01-01

    A review which traces the development of high power pulsed accelerators from the original inception at the Atomic Weapons Research Establishment, Aldermaston, England, for Bremsstrahlung output, through the low impedance accelerators, to the double-sided accelerators for fusion will be given. Proto II is presently being assembled at Sandia and preliminary testing on the Marx has been completed. Examples of various techniques will be shown from Sandia accelerators. Requirements for accelerators capable of achieving fusion levels will be developed and problem areas outlined. The diode insulator flashover problem presently limits the maximum current available from the accelerators

  11. A Pulsed Sphere Tutorial

    Energy Technology Data Exchange (ETDEWEB)

    Cullen, Dermott E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-01-30

    Here I attempt to explain what physically happens when we pulse an object with neutrons, specifically what we expect the time dependent behavior of the neutron population to look like. Emphasis is on the time dependent emission of both prompt and delayed neutrons. I also describe how the TART Monte Carlo transport code models this situation; see the appendix for a complete description of the model used by TART. I will also show that, as we expect, MCNP and MERCURY, produce similar results using the same delayed neutron model (again, see the appendix).

  12. PULSE SYNTHESIZING GENERATOR

    Science.gov (United States)

    Kerns, Q.A.

    1963-08-01

    >An electronlc circuit for synthesizing electrical current pulses having very fast rise times includes several sinewave generators tuned to progressively higher harmonic frequencies with signal amplitudes and phases selectable according to the Fourier series of the waveform that is to be synthesized. Phase control is provided by periodically triggering the generators at precisely controlled times. The outputs of the generators are combined in a coaxial transmission line. Any frequency-dependent delays that occur in the transmission line can be readily compensated for so that the desired signal wave shape is obtained at the output of the line. (AEC)

  13. Charge pulse preamplifier

    International Nuclear Information System (INIS)

    Libs, Gerard.

    1973-01-01

    A charge pulse preamplifier with very low background noise is described. The inlet stage of that preamplifier comprises a cooled field-effect transistor receiving the signal to be amplified at its gate input. Preferably, the charge resistor of said transistor is a field effect transistor, the source inlet of which is connected to the drain inlet of the former transistor through a self-induction coil and a resistor mounted in series. This can be applied to the treatment of the signals delivered by a particle detector in the form of a semi-conductor [fr

  14. A new type of one-dimensional compound: Structure of Nb4(Te2)4Te4I

    International Nuclear Information System (INIS)

    Deng Shuiquan; Zhuang Honghui; Lu Canzhong; Huang Jinshun; Huang Jingling

    1993-01-01

    The new infinite-chain niobium telluride iodide has been prepared by reaction of the elements at 893 K. Nb 4 (Te 2 ) 4 Te 4 I represents a new one-dimensional structure type. The structure consists of [Nb 4 (Te 2 ) 4 Te 4 I] ∞ chains which are formed by the four-nuclear butterfly cluster units 'Nb 4 (Te 2 ) 4 Te 4 ' with the I atoms bridging between different cluster units. (orig.)

  15. Narrowband pulse-enhanced upconversion of chirped broadband pulses

    International Nuclear Information System (INIS)

    Zhao, Kun; Yuan, Peng; Zhong, Haizhe; Zhang, Dongfang; Zhu, Heyuan; Qian, Liejia; Chen, Liezun; Wen, Shuangchun

    2010-01-01

    We propose and demonstrate an efficient sum-frequency mixing scheme based on narrowband and chirped broadband pulses. It combines the advantages of wider spectral acceptance bandwidth and of alleviating the temporal walk-off, which are both beneficial to higher conversion efficiency. Chirped sum-frequency pulses at 455 nm with energy up to 360 µJ, corresponding to a conversion efficiency of ∼ 40%, are obtained and the pulses can be compressed to ∼ 110 fs. The sum-frequency mixing scheme may provide a promising route to the efficient generation of deep-ultraviolet femtosecond pulses

  16. MoTe2 saturable absorber for passively Q-switched Ho,Pr:LiLuF4 laser at ∼3 μm

    Science.gov (United States)

    Yan, Zhengyu; Li, Tao; Zhao, Shengzhi; Yang, Kejian; Li, Dechun; Li, Guiqiu; Zhang, Shuaiyi; Gao, Zijing

    2018-03-01

    Multilayer molybdenum ditelluride (MoTe2) nanosheets were prepared by liquid-phase exfoliation (LPE) method. A YAG-based MoTe2 saturable absorption (SA) was consequently fabricated. The MoTe2-SA was employed in a passively Q-switched Ho,Pr:LiLuF4 laser at 2.95 μm. Under the absorbed pump power of 3.8 W, an average output power of 90 mW was achieved. The shortest pulse duration of 670 ns was generated with an output power of 73 mW and a repetition rate of 76.46 kHz, corresponding to a pulse energy of 0.95 μJ.

  17. Pulse Power Modulator development for the CLIC Damping Ring Kickers

    CERN Document Server

    Holma, Janne

    2012-01-01

    The Compact Linear Collider (CLIC) study is exploring the scheme for an electron-positron collider with high luminosity (10-34 – 10-35 cm-2s-1) and a nominal centre-of-mass energy of 3 TeV: CLIC would complement LHC physics in the multi-TeV range. The CLIC design relies on Pre-Damping Rings (PDR) and Damping Rings (DR) to achieve the very low emittance, through synchrotron radiation, needed for the luminosity requirements of CLIC. To limit the beam emittance blow-up due to oscillations, the pulse power modulators for the DR kickers must provide extremely flat, high-voltage pulses: the 2 GHz specification called for a 160 ns duration flat-top of 12.5 kV, 250 A, with a combined ripple and droop of not more than ±0.02 %. In order to meet these demanding specifications, a combination of broadband impedance matching, optimized electrical circuit layout and advanced control techniques is required. A solid-state modulator, the inductive adder, is the most promising approach to meeting the demanding specifications...

  18. Characteristics of laser irradiated Hg sub 0 ,835 Cd sub 0 ,165 Te analysed by resonant Raman spectroscopy

    International Nuclear Information System (INIS)

    Scepanovic, M.; Jevtic, M.

    1998-01-01

    The characteristics of Hg sub 0 ,835 Cd sub 0 ,165 Te sample irradiated by a nanosecond Nd: YAG laser pulse are investigated using a resonant Raman spectroscopy. The pulse energy density of 100 mJ/cm sup 2 is close to the energy threshold of material melting under the irradiated conditions. The presented Raman spectra of the unirradiated and irradiated sample parts point out that the laser irradiation induced a little concentration change in the surface sample layers without the essential structural changes (author)

  19. Selection of optimal pulse sequences for conventional and dynamic MR imaging with Gd-DTPA; A fundamental study

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, Miho; Kita, Keisuke; Maeda, Masayuki (Wakayama Medical Coll. (Japan)) (and others)

    1989-11-01

    Gadolinium-DTPA (Gd-DTPA) enhances contrast between tissues in magnetic resonance (MR) imaging. The enhancement of tissues depends partly upon the pulse sequences, and the optimal pulse sequence is also influenced by the tissue cncentration of Gd-DTPA. We prepared phantoms of 25% albumin solutions with various concentrations of Gd-DTPA, and imaged them using various pulse sequences with 1.5-T MR system. We also performed MR imaging of 16 patients with tumors (10 brain tumors and 6 hepatic tumors) before and after intravenous administration of Gd-DTPA (0.1 mmol/kg); 6 patients with hepatic tumors underwent dynamic MR imaging during suspended respiration. We made a theoretical equation to calculate the concentration of Gd-DTPA and estimated its tissue concentration in tumors at 0{approx}0.2 mmol/kg. Within these tissue concentrations, the enhancement-to-noise (E/N) ratio was larger in FISP (flip angle of 90deg, TR pf 300 msec, minimal TE) and SE (TR of 400 msec, minimal TE) sequences than in other sequences observed. These sequences may be preferable for conventional enhanced-MRI. Among the pulse sequences with TR of less than 100 msec, FISP (flip angle of 90deg, TR of less than 100 msec, minimal TE) had the largest E/N ratio; which may be useful for dynamic MRI during suspended respiration. The importance of selecting the optimal pulse sequences according to the imaging modality used will be discussed. (author).

  20. Supercoherent phenomena in pulsed power

    International Nuclear Information System (INIS)

    O'Rourke, R.C.

    1983-01-01

    This chapter proposes the formulation of programs of basic physics research to transform Pulsed Power Technology (PPT) to Pulsed Power Science and Technology (PPS and T) by formulating the laws of the quantized microscopic electromagnetic field; applying the microscopic electromagnetic field theory to the generation, propagation and deposition of pulses in nonlinear networks; learning more about the basic super coherent ''micro-structure'' in space and time of the many-photon states of pulsed laser beams; learning more about the basic super coherent ''micro-structure'' in space and time of the many-electronstates of pulsed electron and ion laser beams; and learning everything about the ''micro-picture'' of so-called ''dielectric breakdown'' and the associated absolute time delays. Promotes the idea that laser, electron and ion beams are similar kinds of pulses in the microscopic electromagnetic field. Presents expression for the microscopic electromagnetic field in order to show the role of supercoherence in PPS and T

  1. Precipitation of Ag2Te in the thermoelectric material AgSbTe2

    International Nuclear Information System (INIS)

    Sugar, Joshua D.; Medlin, Douglas L.

    2009-01-01

    The microstructure of AgSbTe 2 , prepared by solidification, is investigated using electron microscopy. During solidification and thermal treatment, the material separates into a two-phase mixture of a rocksalt phase, which is Ag 22 Sb 28 Te 50 , and silver telluride, Ag 2 Te. Ag 2 Te formation results either from eutectic solidification (large lamellar structures), or by solid-state precipitation (fine-scale particles). The crystal structure of the AgSbTe 2 phase determined by electron diffraction is consistent with a rocksalt structure that has a disordered cation sublattice. A preferred crystallographic orientation relationship at the interface between the matrix and the low-temperature monoclinic Ag 2 Te phase is defined and discussed. This orientation relationship is observed for both second-phase morphologies. In both cases, the orientation relationship originates from a topotactic (cube-on-cube) alignment of the Te sublattices in the initially cubic Ag 2 Te and the matrix at elevated temperature. This Te sublattice alignment is retained as the Ag 2 Te undergoes a cubic-to-monoclinic transformation during cooling. This orientation relationship is observed for both second-phase morphologies.

  2. Pulsar TeV Halos Explain the Diffuse TeV Excess Observed by Milagro.

    Science.gov (United States)

    Linden, Tim; Buckman, Benjamin J

    2018-03-23

    Milagro observations have found bright, diffuse TeV emission concentrated along the galactic plane of the Milky Way. The intensity and spectrum of this emission is difficult to explain with current models of hadronic γ-ray production, and has been named the "TeV excess." We show that TeV emission from pulsars naturally explains this excess. Recent observations have detected "TeV halos" surrounding pulsars that are either nearby or particularly luminous. Extrapolating this emission to the full population of Milky Way pulsars indicates that the ensemble of "subthreshold" sources necessarily produces bright TeV emission diffusively along the Milky Way plane. Models indicate that the TeV halo γ-ray flux exceeds that from hadronic γ rays above an energy of ∼500  GeV. Moreover, the spectrum and intensity of TeV halo emission naturally matches the TeV excess. Finally, we show that upcoming HAWC observations will resolve a significant fraction of the TeV excess into individual TeV halos, conclusively confirming, or ruling out, this model.

  3. Bipolar pulse forming line

    Science.gov (United States)

    Rhodes, Mark A.

    2008-10-21

    A bipolar pulse forming transmission line module for linear induction accelerators having first, second, third, fourth, and fifth planar conductors which form an interleaved stack with dielectric layers between the conductors. Each conductor has a first end, and a second end adjacent an acceleration axis. The first and second planar conductors are connected to each other at the second ends, the fourth and fifth planar conductors are connected to each other at the second ends, and the first and fifth planar conductors are connected to each other at the first ends via a shorting plate adjacent the first ends. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short a high voltage from the first end of the third planar conductor to the first end of the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral. Improved access to the switch is enabled by an aperture through the shorting plate and the proximity of the aperture to the switch.

  4. Heat driven pulse pump

    Science.gov (United States)

    Benner, Steve M (Inventor); Martins, Mario S. (Inventor)

    2000-01-01

    A heat driven pulse pump includes a chamber having an inlet port, an outlet port, two check valves, a wick, and a heater. The chamber may include a plurality of grooves inside wall of the chamber. When heated within the chamber, a liquid to be pumped vaporizes and creates pressure head that expels the liquid through the outlet port. As liquid separating means, the wick, disposed within the chamber, is to allow, when saturated with the liquid, the passage of only liquid being forced by the pressure head in the chamber, preventing the vapor from exiting from the chamber through the outlet port. A plurality of grooves along the inside surface wall of the chamber can sustain the liquid, which is amount enough to produce vapor for the pressure head in the chamber. With only two simple moving parts, two check valves, the heat driven pulse pump can effectively function over the long lifetimes without maintenance or replacement. For continuous flow of the liquid to be pumped a plurality of pumps may be connected in parallel.

  5. Compensated pulsed alternator

    International Nuclear Information System (INIS)

    Weldon, W.F.; Driga, M.D.; Woodson, H.H.

    1980-01-01

    This invention relates to an electromechanical energy converter with inertial energy storage. The device, a single phase, two or multi-pole alternator with stationary field coils, and a rotating armature is provided. The rotor itself may be of laminated steel for slower pulses or for faster pulses should be nonmagnetic and electrically nonconductive in order to allow rapid penetration of the field as the armature coil rotates. The armature coil comprises a plurality of power generating conductors mounted on the rotor. The alternator may also include a stationary or counterrotating compensating coil to increase the output voltage thereof and to reduce the internal impedance of the alternator at the moment of peak output. As the machine voltage rises sinusoidally, an external trigger switch is adapted to be closed at the appropriate time to create the desired output current from said alternator to an external load circuit, and as the output current passes through zero a self-commutating effect is provided to allow the switch to disconnect the generator from the external circuit

  6. RHEED studies of MBE growth mechanisms of CdTe and CdMnTe

    Energy Technology Data Exchange (ETDEWEB)

    Waag, A.; Behr, T.; Litz, T.; Kuhn-Heinrich, B.; Hommel, D.; Landwehr, G. (Physikalisches Inst., Univ. Wuerzburg (Germany))

    1993-01-30

    We report on reflection high energy electron diffraction (RHEED) studies of molecular beam epitaxy (MBE) growth of CdTe and CdMnTe on (100) oriented CdTe substrates. RHEED oscillations were measured for both the growth and desorption of CdTe and CdMnTe as a function of flux and temperature. For the first time, the influence of laser and electron irradiation on the growth rate, as well as desorption, of CdTe is studied in detail using RHEED oscillations. We found a very small effect on the growth rate as well as on the CdTe desorption rate. The growth rate of CdTe was determined for different temperatures and CdTe flux ratios. The obtained experimental results are compared with a kinetic growth model to get information on the underlying growth processes, taking into account the influence of a precursor by including surface diffusion. From the comparison between model and experimental results the sticking coefficients of Cd and Te are determined. The growth rate of CdMnTe increases with Mn flux. This dependence can be used to calibrate the Mn content during growth by comparing the growth rate of CdTe with the growth rate of CdMnTe. The change in growth rate has been correlated with Mn content via photoluminescence measurements. In addition, the sticking coefficient of Mn is derived by comparing experimental results with a kinetic growth model. For high manganese content a transition to three-dimensional growth occurs. (orig.).

  7. Pulsed neutron sources at KAON

    International Nuclear Information System (INIS)

    Thorson, I.M.; Egelstaff, P.A.; Craddock, M.K.

    1991-01-01

    The proposed KAON Factory facility at TRIUMF consists of a number of synchrotrons and storage rings which offer proton beams of energies between 0.45 and 30 GeV with varying pulse amplitudes, widths and repetition rates. Various possibilities for feeding these beams to a pulsed neutron facility and their potential for future development are examined. The incremental cost of such a pulsed neutron facility is estimated approximately. (author)

  8. Assembly delay line pulse generators

    CERN Multimedia

    CERN PhotoLab

    1971-01-01

    Assembly of six of the ten delay line pulse generators that will power the ten kicker magnet modules. One modulator part contains two pulse generators. Capacitors, inductances, and voltage dividers are in the oil tank on the left. Triggered high-pressure spark gap switches are on the platforms on the right. High voltage pulse cables to the kicker magnet emerge under the spark gaps. In the centre background are the assembled master gaps.

  9. Si-Sb-Te materials for phase change memory applications

    International Nuclear Information System (INIS)

    Rao Feng; Song Zhitang; Ren Kun; Zhou Xilin; Cheng Yan; Wu Liangcai; Liu Bo

    2011-01-01

    Si-Sb-Te materials including Te-rich Si 2 Sb 2 Te 6 and Si x Sb 2 Te 3 with different Si contents have been systemically studied with the aim of finding the most suitable Si-Sb-Te composition for phase change random access memory (PCRAM) use. Si x Sb 2 Te 3 shows better thermal stability than Ge 2 Sb 2 Te 5 or Si 2 Sb 2 Te 6 in that Si x Sb 2 Te 3 does not have serious Te separation under high annealing temperature. As Si content increases, the data retention ability of Si x Sb 2 Te 3 improves. The 10 years retention temperature for Si 3 Sb 2 Te 3 film is ∼ 393 K, which meets the long-term data storage requirements of automotive electronics. In addition, Si richer Si x Sb 2 Te 3 films also show improvement on thickness change upon annealing and adhesion on SiO 2 substrate compared to those of Ge 2 Sb 2 Te 5 or Si 2 Sb 2 Te 6 films. However, the electrical performance of PCRAM cells based on Si x Sb 2 Te 3 films with x > 3.5 becomes worse in terms of stable and long-term operations. Si x Sb 2 Te 3 materials with 3 < x < 3.5 are proved to be suitable for PCRAM use to ensure good overall performance.

  10. THIN SECTION DESCRIPTIONS: LITTLE UTE AND SLEEPING UTE FIELDS, MONTEZUMA COUNTY, COLORADO

    Energy Technology Data Exchange (ETDEWEB)

    David E. Eby; Laura L. Wray

    2003-12-01

    Over 400 million barrels (64 million m{sup 3}) of oil have been produced from the shallow-shelf carbonate reservoirs in the Pennsylvanian (Desmoinesian) Paradox Formation in the Paradox Basin, Utah and Colorado. With the exception of the giant Greater Aneth field, the other 100 plus oil fields in the basin typically contain 2 to 10 million barrels (0.3-1.6 million m{sup 3}) of original oil in place. Most of these fields are characterized by high initial production rates followed by a very short productive life (primary), and hence premature abandonment. Only 15 to 25 percent of the original oil in place is recoverable during primary production from conventional vertical wells. An extensive and successful horizontal drilling program has been conducted in the giant Greater Aneth field in Utah (figure 1). However, to date, only two horizontal wells have been drilled in small Ismay and Desert Creek fields. The results from these wells were disappointing due to poor understanding of the carbonate facies and diagenetic fabrics that create reservoir heterogeneity. These small fields, and similar fields in the basin, are at high risk of premature abandonment. At least 200 million barrels (31.8 million m{sup 3}) of oil will be left behind in these small fields because current development practices leave compartments of the heterogeneous reservoirs undrained. Through proper geological evaluation of the reservoirs, production may be increased by 20 to 50 percent through the drilling of low-cost single or multilateral horizontal legs from existing vertical development wells. In addition, horizontal drilling from existing wells minimizes surface disturbances and costs for field development, particularly in the environmentally sensitive areas of southeastern Utah and southwestern Colorado.

  11. Geotechnical sounding of the UTE-Uruguay dams; La auscultacion geotecnica de las presas de UTE

    Energy Technology Data Exchange (ETDEWEB)

    Patrone Matteo, Julio C.; Rosriguez Pastorino, Sandra; Mandia Bica, Magdalena [Administracion Nacional de Usinas e Transmisiones Electricas (UTE), Montevideo (Uruguay)]. E-mail: gsgh@ute.com.uy

    1998-07-01

    This paper addresses specifically to the soil dams, and soil dikes of the Constitucion Dam, which is presently the most instrumented, considering that the set of inspection routine and instrumentation data, including the interpretation and behaviour evaluation, are the basis for the dam sounding.

  12. Time resolution improvement of Schottky CdTe PET detectors using digital signal processing

    International Nuclear Information System (INIS)

    Nakhostin, M.; Ishii, K.; Kikuchi, Y.; Matsuyama, S.; Yamazaki, H.; Torshabi, A. Esmaili

    2009-01-01

    We present the results of our study on the timing performance of Schottky CdTe PET detectors using the technique of digital signal processing. The coincidence signals between a CdTe detector (15x15x1 mm 3 ) and a fast liquid scintillator detector were digitized by a fast digital oscilloscope and analyzed. In the analysis, digital versions of the elements of timing circuits, including pulse shaper and time discriminator, were created and a digital implementation of the Amplitude and Rise-time Compensation (ARC) mode of timing was performed. Owing to a very fine adjustment of the parameters of timing measurement, a good time resolution of less than 9.9 ns (FWHM) at an energy threshold of 150 keV was achieved. In the next step, a new method of time pickoff for improvement of timing resolution without loss in the detection efficiency of CdTe detectors was examined. In the method, signals from a CdTe detector are grouped by their rise-times and different procedures of time pickoff are applied to the signals of each group. Then, the time pickoffs are synchronized by compensating the fixed time offset, caused by the different time pickoff procedures. This method leads to an improved time resolution of ∼7.2 ns (FWHM) at an energy threshold of as low as 150 keV. The methods presented in this work are computationally fast enough to be used for online processing of data in an actual PET system.

  13. Stratigraphy, landsnail faunas, and paleoenvironmental history of coastal dunefields at Te Werahi, northernmost New Zealand

    International Nuclear Information System (INIS)

    Brook, F.J.

    1999-01-01

    During Quaternary time, the history of the Te Werahi area included episodes of dunefield formation alternating with periods of extensive erosion of sand cover. Dune units of last interglacial age and older crop out as isolated erosional remnants within and adjacent to an extensive Holocene dunefield. The latter had begun to form by at least 4000 years BP, and dune mobilisation continued until about 1800 years BP, possibly with increased dune movement after 3000 years BP. A smaller Holocene dunefield on Motuopao Island also formed before about 1800 years BP. After 1800 years BP, the Te Werahi and Motuopao dunefields entered a stable phase that persisted until about 450 years BP, followed by dune remobilisation and erosion that has continued to the present day. Analysis of fossil landsnail faunas indicates that forest was widespread in the Te Werahi area in mid Holocene time, was mostly over-run by dunes by about 1900 years BP, and then locally re-established on the dunefield between about 1800 and 800 year BP. That dune forest was destroyed between 800 and 550 years BP, probably as a result of anthropic firing following Polynesian settlement, and has not subsequently re-established. Vegetation disturbance on the Te Werahi dunefield since at least 4000 years BP has resulted in cumulative extinctions and impoverishment of native landsnail faunas, especially during major extinction pulses before 1900 years BP and between 800 and 550 years BP. (author). 43 refs., 6 figs., 2 tabs

  14. Ultrafast optical control of the electronic properties of ZrTe5

    Energy Technology Data Exchange (ETDEWEB)

    Crepaldi, Alberto; Cilento, Federico [Elettra-Sincrotrone Trieste (Italy); Manzoni, Giulia; Sterzi, Andrea; Diego, Michele [Universita degli Studi di Trieste (Italy); Kuhn, Timo; Gragnaniello, Luca; Fonin, Mikhail [University of Konstanz (Germany); Autes, Gabriel; Bugnon, Philippe; Magrez, Arnaud; Berger, Helmuth; Yazyev, Oleg; Grioni, Marco [EPFL (Switzerland); Zacchigna, Michele [C.N.R.-I.O.M. (Italy); Parmigiani, Fulvio [Elettra-Sincrotrone Trieste (Italy); Universita degli Studi di Trieste (Italy)

    2016-07-01

    ZrTe5 has recently attracted considerable interest owing to some unique, albeit only partially understood, properties. The electrical resistivity exhibits a peak at a temperature where the nature of the charge carriers changes from holes to electrons. The observed negative magneto-resistance has been attributed to the presence of Dirac particles, either three-dimensional or two-dimensional and spin-polarized. Our time and angle-resolved photoelectron spectroscopy (tr-ARPES) study has addressed the origin of the anomalous transport behavior of ZrTe5, while showing the possibility to control the electronic properties of this material via sub-ps IR laser pulses. These observations open the way to the exploitation of ZrTe5 as a platform for magnetoelectric optical and thermoelectric transport applications. Finally, by combining ab initio calculations, ARPES and scanning tunneling microscopy (STM) we are contributing to shed light on the topological nature of ZrTe5, which is shown to be close to transition between strong and weak topological insulator phases.

  15. Powerful nanosecond pulse train generator

    International Nuclear Information System (INIS)

    Isakov, I.F.; Logachev, E.I.; Opekunov, M.S.; Pechenkin, S.A.; Remnev, G.E.; Usov, Yu.P.

    1987-01-01

    A generator permitting to shape on the load pulsed with the repetition frequency of 10 3 -10 6 Hz and more is described. The amplitude of shaped voltage pulses is up to 150 kV at pulse duration equal to 50 ns. The generator comprises connected in-series with the load two shaping and two transmission lines realized on the base of the KVI-300 low-ohmic cable. The shaping lines are supplied from two independently connected pulse voltage generators for obtaining time interval between pulses > 10 -6 s; they may be also supplied from one generator for obtaining time interval -6 s. At the expense of reducing losses in the discharge circuit the amplitude of the second pulse grows with increase of time interval between pulses up to 300 ns, further on the curve flat-topping exists. The described generator is used in high-current accelerators, in which the primary negative pulse results in generation of explosive-emission plasma, and the second positive pulse provides ion beam shaping including ions of heavy metal used for production of a potential electrode. The generator multipulse mode is used for successive ion acceleration in the transport system

  16. Growth and optical properties of CdTe quantum dots in ZnTe nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Wojnar, Piotr; Janik, Elzbieta; Baczewski, Lech T.; Kret, Slawomir; Karczewski, G.; Wojtowicz, Tomasz [Institute of Physics, Polish Academy of Sciences, Al Lotnikow 32/46, 02-668 Warsaw (Poland); Goryca, Mateusz; Kazimierczuk, Tomasz; Kossacki, Piotr [Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul Hoza 69, 00-681 Warsaw (Poland)

    2011-09-12

    We report on the formation of optically active CdTe quantum dots in ZnTe nanowires. The CdTe/ZnTe nanostructures have been grown by a gold nanocatalyst assisted molecular beam epitaxy in a vapor-liquid solid growth process. The presence of CdTe insertions in ZnTe nanowire results in the appearance of a strong photoluminescence band in the 2.0 eV-2.25 eV energy range. Spatially resolved photoluminescence measurements reveal that this broad emission consists of several sharp lines with the spectral width of about 2 meV. The large degree of linear polarization of these individual emission lines confirms their nanowire origin, whereas the zero-dimensional confinement is proved by photon correlation spectroscopy.

  17. Electrical and optical properties of SnEuTe and SnSrTe films

    Science.gov (United States)

    Ishida, Akihiro; Tsuchiya, Takuro; Yamada, Tomohiro; Cao, Daoshe; Takaoka, Sadao; Rahim, Mohamed; Felder, Ferdinand; Zogg, Hans

    2010-06-01

    The SnTe, Sn1-xEuxTe and Sn1-xSrxTe (x<0.06) films were prepared by hot wall epitaxy. The ternary alloy films prepared in cation rich condition had hole concentration around 1×1019 cm-3 with high mobility exceeding 2000 cm2/V s at room temperature. Optical transmission spectra were also measured in the temperature range from 100 to 400 K and compared with theoretical calculations. Optical transmission spectra of the SnTe were simulated successfully assuming bumped band edge structures. A band inversion model was proposed for the Sn1-xEuxTe and Sn1-xSrxTe systems, and the optical transmission spectra were also simulated successfully assuming the band inversion model.

  18. CdTe in photoconductive applications. Fast detector for metrology and X-ray imaging

    International Nuclear Information System (INIS)

    Cuzin, M.

    1991-01-01

    Operating as a photoconductor, the sensitivity and the impulse response of semi-insulating materials greatly depend on the excitation duration compared to electron and hole lifetimes. The requirement of ohmic contact is shortly discussed. Before developing picosecond measurements with integrated autocorrelation system, this paper explains high energy industrial tomographic application with large CdTe detectors (25x15x0.9 mm 3 ). The excitation is typically μs range. X-ray flash radiography, with 10 ns burst, is in an intermediate time domain where excitation is similar to electron life-time. In laser fusion experiment excitation is in the range of 50 ps and we develop photoconductive devices able to study very high speed X-ray emission time behaviour. Thin polycristalline MOCVD CdTe films with picosecond response are suitable to perform optical correlation measurements of single shot pulses with a very large bandwidth (- 50 GHz)

  19. Local polarization phenomena in In-doped CdTe x-ray detector arrays

    International Nuclear Information System (INIS)

    Sato, Toshiyuki; Sato, Kenji; Ishida, Shinichiro; Kiri, Motosada; Hirooka, Megumi; Yamada, Masayoshi; Kanamori, Hitoshi

    1995-01-01

    Local polarization phenomena have been studied in detector arrays with the detector element size of 500 microm x 500 microm, which are fabricated from high-resistivity In-doped CdTe crystals grown by the vertical Bridgman technique. It has been found for the first time that a polarization effect, which is characterized by a progressive decrease of the pulse counting rate with increasing photon fluence, strongly depends on the detector elements, that is, the portion of crystals used. The influence of several parameters, such as the applied electric field strength, time, and temperature, on this local polarization effect is also investigated. From the photoluminescence measurements of the inhomogeneity of In dopant, it is concluded that the local polarization effect observed here originates from a deep level associated with In dopant in CdTe crystals

  20. RF power sources for 5--15 TeV linear colliders

    International Nuclear Information System (INIS)

    Wilson, P.B.

    1996-09-01

    After outlining the design of the NLC rf system at 1 TeV, the possibility of a leap in linear collider energy into the 5--15 TeV energy range is considered. To keep the active accelerator length and ac wall-plug power within reasonable bounds, higher accelerating gradients at higher rf frequencies will be necessary. Scaling relations are developed for basic rf system parameters as a function of frequency, and some specific parameter examples are given for colliders at 34 Ghz and 91 Ghz. Concepts for rf pulse compression system design and for high power microwave sources at 34 Ghz (for example sheet-beam and multiple-beam klystrons) are briefly discussed

  1. Front-end electronics for the readout of CdZnTe sensors

    CERN Document Server

    Moraes, D; Rudge, A

    2006-01-01

    The CERN_DxCTA is a front-end ASIC optimized for the readout of CdZn Te sensors. The chip is implemented in 0.25 mum CMOS technology. The circuit consists of 128 channels equipped with a transimpedance amplifier followed by a gain-shaper stage with 20 ns peaking time and two discriminators, allowing two threshold settings. Each discriminator includes a 5-bit trim DAC and is followed by an 18-bit static ripple-counter. The channel architecture is optimized for the detector characteristics in order to achieve the best energy resolution at counting rates of up to 5 M counts/second. Complete evaluation of the circuit is presented using electronic pulses and Cd ZnTe pixel detectors.

  2. Structural and superconducting properties of epitaxial Fe{sub 1+y}Se{sub 1-x}Te{sub x} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Richter, Stefan; Yuan, Feifei; Grinenko, Vadim; Huehne, Ruben [Institute for Metallic Materials, IFW Dresden (Germany); Sala, Alberto; Putti, Marina [Dipartimento di Fisica, Universita di Genova (Italy)

    2015-07-01

    The iron based superconductor Fe(Se,Te) is in the center of much ongoing research. The reason for this is on the one hand its simple crystal structure, that consists only of stacked Fe(Se,Te) layers so that structural and superconducting properties can be connected more easily, on the other hand FeSe itself shows a high sensibility for strain and changes in stoichiometry and can have potentially very high critical temperatures under hydrostatic pressure or in monolayers. We investigate epitaxial thin films of Fe{sub 1+y}Se{sub 1-x}Te{sub x} grown by pulsed laser deposition on different single crystalline substrates. A high crystalline quality and a superconducting transition of up to about 20 K can be achieved using optimized deposition parameters. The influence of growth conditions, Te-doping, film thickness and post growth oxygen treatment on the structural and superconducting properties on these films will be presented in detail.

  3. Mid-infrared PbTe vertical external cavity surface emitting laser on Si-substrate with above 1 W output power

    Science.gov (United States)

    Rahim, M.; Fill, M.; Felder, F.; Chappuis, D.; Corda, M.; Zogg, H.

    2009-12-01

    Mid-infrared vertical external cavity surface emitting lasers (VECSELs) emitting above 1 W output power in pulsed mode and up to 17 mW in continuous mode at -172 °C were realized. Emission wavelength changes from 5 μm at -172 °C to 3.6 μm at 20 °C heat sink temperature. The active medium is a one wavelength thick PbTe layer grown by molecular beam epitaxy on a Si-substrate. It is followed by a 2.5 pair Pb1-yEuyTe/EuTe epitaxial Bragg mirror. The cavity is completed with an external curved Pb1-yEuyTe/BaF2 mirror. The VECSEL is optically pumped with 1.55 μm wavelength laser and In-soldered to Cu heat sink. No microstructural processing is needed.

  4. Digital pulse shape discrimination

    International Nuclear Information System (INIS)

    Miller, L. F.; Preston, J.; Pozzi, S.; Flaska, M.; Neal, J.

    2007-01-01

    Pulse-shape discrimination (PSD) has been utilised for about 40 years as a method to obtain estimates for dose in mixed neutron and photon fields. Digitizers that operate close to GHz are currently available at a reasonable cost, and they can be used to directly sample signals from photomultiplier tubes. This permits one to perform digital PSD rather than the traditional, and well-established, analogous techniques. One issue that complicates PSD for neutrons in mixed fields is that the light output characteristics of typical scintillators available for PSD, such as BC501A, vary as a function of energy deposited in the detector. This behaviour is more easily accommodated with digital processing of signals than with analogous signal processing. Results illustrate the effectiveness of digital PSD. (authors)

  5. Pulsed Compression Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Roestenberg, T. [University of Twente, Enschede (Netherlands)

    2012-06-07

    The advantages of the Pulsed Compression Reactor (PCR) over the internal combustion engine-type chemical reactors are briefly discussed. Over the last four years a project concerning the fundamentals of the PCR technology has been performed by the University of Twente, Enschede, Netherlands. In order to assess the feasibility of the application of the PCR principle for the conversion methane to syngas, several fundamental questions needed to be answered. Two important questions that relate to the applicability of the PCR for any process are: how large is the heat transfer rate from a rapidly compressed and expanded volume of gas, and how does this heat transfer rate compare to energy contained in the compressed gas? And: can stable operation with a completely free piston as it is intended with the PCR be achieved?.

  6. Pulse-shaping strategies in short-pulse fiber amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Schimpf, Damian Nikolaus

    2010-02-09

    Ultrashort pulse lasers are an important tool in scientific and industrial applications. However, many applications are demanding higher average powers from these ultrashort pulse sources. This can be achieved by combining direct diode pumping with novel gain media designs. In particular, ultrashort pulse fiber lasers are now delivering average powers in the kW range. However, the design of fiber lasers, producing pulses with high peak-powers, is challenging due to the impact of nonlinear effects. To significantly reduce these detrimental effects in ultrashort pulse fiber amplifers, the combination of chirped pulse amplification (CPA) and large mode area fibers is employed. Using these methods, the pulse energy of fiber lasers has been steadily increasing for the past few years. Recently, a fiber-based CPA-system has been demonstrated which produces pulse energies of around 1 mJ. However, both the stretching and the enlargement of the mode area are limited, and therefore, the impact of nonlinearity is still noticed in systems employing such devices. The aim of this thesis is the analysis of CPA-systems operated beyond the conventional nonlinear limit, which corresponds to accumulated nonlinear phase-shifts around 1 rad. This includes a detailed discussion of the influence of the nonlinear effect self-phase modulation on the output pulse of CPA-systems. An analytical model is presented. Emphasis is placed on the design of novel concepts to control the impact of self-phase modulation. Pulse-shaping is regarded as a powerful tool to accomplish this goal. Novel methods to control the impact of SPM are experimentally demonstrated. The design of these concepts is based on the theoretical findings. Both amplitude- and phase-shaping are studied. Model-based phase-shaping is implemented in a state-of-the-art fiber CPA-system. The influence of the polarization state is also highlighted. Additionally, existing techniques and recent advances are put into context. (orig.)

  7. Pulse-shaping strategies in short-pulse fiber amplifiers

    International Nuclear Information System (INIS)

    Schimpf, Damian Nikolaus

    2010-01-01

    Ultrashort pulse lasers are an important tool in scientific and industrial applications. However, many applications are demanding higher average powers from these ultrashort pulse sources. This can be achieved by combining direct diode pumping with novel gain media designs. In particular, ultrashort pulse fiber lasers are now delivering average powers in the kW range. However, the design of fiber lasers, producing pulses with high peak-powers, is challenging due to the impact of nonlinear effects. To significantly reduce these detrimental effects in ultrashort pulse fiber amplifers, the combination of chirped pulse amplification (CPA) and large mode area fibers is employed. Using these methods, the pulse energy of fiber lasers has been steadily increasing for the past few years. Recently, a fiber-based CPA-system has been demonstrated which produces pulse energies of around 1 mJ. However, both the stretching and the enlargement of the mode area are limited, and therefore, the impact of nonlinearity is still noticed in systems employing such devices. The aim of this thesis is the analysis of CPA-systems operated beyond the conventional nonlinear limit, which corresponds to accumulated nonlinear phase-shifts around 1 rad. This includes a detailed discussion of the influence of the nonlinear effect self-phase modulation on the output pulse of CPA-systems. An analytical model is presented. Emphasis is placed on the design of novel concepts to control the impact of self-phase modulation. Pulse-shaping is regarded as a powerful tool to accomplish this goal. Novel methods to control the impact of SPM are experimentally demonstrated. The design of these concepts is based on the theoretical findings. Both amplitude- and phase-shaping are studied. Model-based phase-shaping is implemented in a state-of-the-art fiber CPA-system. The influence of the polarization state is also highlighted. Additionally, existing techniques and recent advances are put into context. (orig.)

  8. BOREAS TE-17 Production Efficiency Model Images

    Data.gov (United States)

    National Aeronautics and Space Administration — A BOREAS version of the Global Production Efficiency Model(www.inform.umd.edu/glopem) was developed by TE-17 to generate maps of gross and net primary production,...

  9. Linear accelerators for TeV colliders

    International Nuclear Information System (INIS)

    Wilson, P.B.

    1985-05-01

    This paper summarizes four tutorial lectures on linear electron accelerators: Electron Linacs for TeV Colliders, Emittance and Damping Rings, Wake Fields: Basic Concepts, and Wake Field Effects in Linacs

  10. Intern transport beter te plannen met computer

    NARCIS (Netherlands)

    Annevelink, E.

    1999-01-01

    Verbetering van intern transport in de potplantenteelt. Door getoetste vuistregels te combineren met toegepaste wiskunde is automatische planning van het intern transport binnen handbereik. Dit leidt tot minder transportbewegingen en tijdsbesparing bij het plannen

  11. Perspective on TeV-scale physics

    International Nuclear Information System (INIS)

    Chanowitz, M.S.

    1989-02-01

    These lectures review theoretical motivations and experimental prospects for the study of TeV-scale physics. Three clues to the importance of TeV physics are discussed: implications of quantum corrections for the masses of a fourth generation quark-lepton family, the gauge hierarchy problem and known solutions, and implications of symmetry and unitarity for the symmetry-breaking sector of the electroweak gauge theory. The experimental prospects are reviewed with emphasis on the multi-TeV pp colliders that may be built in the 1990's. The topics include new phenomena that might occur - e.g., a fourth generation, heavy gauge bosons, composite structure, and supersymmetry - as well as the signals of the unknown SU(2)/sub L/ /times/ U(1)/sub Y/ breaking mechanism that must occur within the TeV domain. 96 refs., 21 figs

  12. Hoe leer je iemand effectief te leren?

    NARCIS (Netherlands)

    Kester, Liesbeth; Koper, Rob; Gijselaers, Jérôme; Bahreini, Kiavash; De Vries, Fred; Wetzels, Sandra; Kirschner, Paul A.; Berkhout, Jeroen; Storm, Jeroen

    2012-01-01

    Kester, L., Koper, R., Gijselaers, J., Bahreini, K., De Vries, F., Berkhout, J., & Storm, J. (2012, 30 maart). Hoe leer je iemand effectief te leren? Masterclass in de OpenU community. Open universiteit, Heerlen, Nederland. Beschikbaar op

  13. TeSLA e-assessment workshop

    NARCIS (Netherlands)

    Janssen, José

    2016-01-01

    Presentatie ten behoeve van de e-assessment workshop voor docenten van de Open Universiteit Nederland betrokken in de eerste TeSLA pilot. Topics: toetsfraude, toetsdesign, technologie voor authenticatie en verificatie van auteurschap.

  14. Fat-suppressed fast spin-echo mid-TE (TE[effective]=34) MR images: comparison with fast spin-echo T2-weighted images for the diagnosis of tears and anatomic variants of the glenoid labrum

    Energy Technology Data Exchange (ETDEWEB)

    Tuite, M J [Dept. of Radiology, Univ. of Wisconsin School of Medicine, Madison (United States); University of Wisconsin Hospital and Clinics, Dept. of Radiology, Madison, WI (United States); Shinners, T J; Hollister, M C [Dept. of Radiology, Univ. of Wisconsin School of Medicine, Madison (United States); Orwin, J F [Dept. of Orthopedic Surgery, University of Wisconsin School of Medicine, Madison (United States)

    1999-12-01

    Objective. To compare the sensitivity, specificity, and accuracy of fat-suppressed fast spin-echo (FSE) mid-TE (TE[effective]=34) images with fat-suppressed FSE T2-weighted images for the diagnosis of labral abnormalities.Design and patients. The study included 27 consecutive patients who had axial fat-suppressed FSE T2-weighted and fat-suppressed FSE mid-TE MR images, and had labral abnormalities diagnosed at arthroscopy. The acquisition time was about 5 min for each sequence, but the mid-TE sequence allowed a higher spatial resolution than the T2-weighted images (256 x 256 versus 256 x 192). Twenty-eight age-matched patients with arthroscopically normal labra were included as a control group. The labrum was graded on the MR images as normal or abnormal separately by two musculoskeletal radiologists who were masked to the history and arthroscopic results. The surgical findings were used as the gold standard for calculating the sensitivity, specificity, and accuracy for interpreting the correct location of a labral abnormality. The sensitivity, specificity, and accuracy for the two sequences were compared with a McNemar test, and significance defined as P<0.05.Results. For observer 1, the sensitivity for labral abnormalities was 0.59 on the T2-weighted images, and 0.78 on the mid-TE images (P=0.12). The specificity was 0.54 for the T2-weighted, and 0.64 for the mid-TE images (P=0.51). The accuracy was 0.56 for the T2-weighted, and 0.71 for the mid-TE images (P=0.08). For observer 2, the sensitivity/specificity/accuracy was 0.67/0.93/0.80 for the T2-weighted, and 0.70/0.86/0.78 for the mid-TE images (all P>0.5).Conclusion. In this small study there is no statistically significant difference for demonstrating labral abnormalities between FSE T2-weighted images, and higher-resolution fat-suppressed FSE mid-TE (TE[effective]=34) images obtained with a similar acquisition time. Although there was a general trend toward higher sensitivity and accuracy with the mid-TE

  15. Matrix-controlled morphology evolution of Te inclusions in CdZnTe single crystal

    International Nuclear Information System (INIS)

    He, Yihui; Jie, Wanqi; Xu, Yadong; Wang, Tao; Zha, Gangqiang; Yu, Pengfei; Zheng, Xin; Zhou, Yan; Liu, Hang

    2012-01-01

    The fine morphologies of microscale Te inclusions in CdZnTe single crystal were investigated to reveal their shape evolution. Such inclusions from crystal ingots with different post-growth cooling rates were analyzed using scanning electron microscopy after surface treatment. A tetrakaidecahedron model embodying {1 0 0} and {1 1 1} matrix facets was developed to interpret the form of the Te inclusions. An entire shape evolution process was also proposed where the final configuration of the Te inclusions was a tetrahedron comprising {1 1 1}B facets.

  16. CuGaTe2-CuAlTe2 system

    International Nuclear Information System (INIS)

    Bodnar', I.V.

    2003-01-01

    The results of studies on the chemical interaction in the CuGaTe 2 -CuAlTe 2 as well as on the thermal and optical properties of the formed solid solutions are presented. It is shown, that continuous number of solid solutions are formed in the CuGaTe 2 -CuAlTe 2 system, which crystallize in the chalcopyrite structure. The diagram of state of this system is plotted. The thermal expansion of these materials is studied through the dilatometric method. The linear dependence of the thermal expansion coefficient on the composition is established. The concentration dependences of the forbidden zone width diverge from the linearity [ru

  17. Formation of self assembled PbTe quantum dots in CdTe on Si(111)

    Science.gov (United States)

    Felder, F.; Fognini, A.; Rahim, M.; Fill, M.; Müller, E.; Zogg, H.

    2010-01-01

    We describe the growth and formation of self assembled PbTe quantum dots in a CdTe host on a silicon (111) substrate. Annealing yields different photoluminescence spectra depending on initial PbTe layer thickness, thickness of the CdTe cap layer and annealing temperature. Generally two distinct emission peaks at ˜0.3 eV and ˜0.45 eV are visible. Model calculations explaining their temperature dependence are performed. The dot size corresponds well with the estimated sizes from electron microscopy images. The quantum dots may be used as absorber within a mid-infrared detector.

  18. Optimal pulse sequence for ferumoxides-enhanced MR imaging used in the detection of hepatocellular carcinoma: a comparative study using seven pulse sequences

    International Nuclear Information System (INIS)

    Kim, Seung Hoon; Choi, Dongil; Lim, Jae Hoon; Lee, Won Jae; Jang, Hyun Jung; Lim, Kyo Keun; Lee, Soon Jin; Cho, Jae Min; Kim, Seung Kwon; Kim, Gab Chul

    2002-01-01

    To identify the optimal pulse sequence for ferumoxides-enhanced magnetic resonance (MR) imaging in the detection of hepatocelluar carcinomas (HCCs). Sixteen patients with 25 HCCs underwent MR imaging following intravenous infusion of ferumoxides. All MR studies were performed on a 1.5-T MR system, using a phased-array coil. Ferumoxides (Feridex IV) at a dose of 15 μmol/Kg was slowly infused intravenously, and axial images of seven sequences were obtained 30 minutes after the end of infusion. The MR protocol included fast spin-echo (FSE) with two echo times (TR3333-8571/TE18 and 90-117), singleshot FSE (SSFSE) with two echo times (TR∞/TE39 and 98), T2-weighted gradient-recalled acquisition in the steady state (GRASS) (TR216/TE20), T2-weighted fast multiplanar GRASS (FMPGR) (TR130/TE8.4-9.5), and T2-weighted fast multiplanar spoiled GRASS (FMPSPGR) (TR130/TE8.4-9.5). Contrast-to-noise ratios (CNRs) of HCCs determined during the imaging sequences formed the basis of quantitative analysis, and images were qualitatively assessed in terms of lesion conspicuity and image artifacts. The diagnostic accuracy of all sequences was assessed using receiver operating characteristic (ROC) analysis. Quantitative analysis revealed that the CNRs of T2-weighted FMPGR and T2-weighted FMPSPGR were significantly higher than those of the other sequences, while qualitative analysis showed that image artifacts were prominent at T2-weighted GRASS imaging. Lesion conspicuity was statistically significantly less clear at SSFSE imaging. In term of lesion detection, T-weighted FMPGR, T2- weighted FMPSPGR, and proton density FSE imaging were statistically superior to the others. T2-weighted FMPGR, T2- weighted FMPSPGR, and proton density FSE appear to be the optimal pulse sequences for ferumoxidesenhanced MR imaging in the detection of HCCs

  19. HgTe based topological insulators

    International Nuclear Information System (INIS)

    Bruene, Christoph

    2014-01-01

    This PhD thesis summarizes the discovery of topological insulators and highlights the developments on their experimental observations. The work focuses on HgTe. The thesis is structured as follows: - The first chapter of this thesis will give a brief overview on discoveries in the field of topological insulators. It focuses on works relevant to experimental results presented in the following chapters. This includes a short outline of the early predictions and a summary of important results concerning 2-dimensional topological insulators while the final section discusses observations concerning 3-dimensional topological insulators. - The discovery of the quantum spin Hall effect in HgTe marked the first experimental observation of a topological insulator. Chapter 2 focuses on HgTe quantum wells and the quantum spin Hall effect. The growth of high quality HgTe quantum wells was one of the major goals for this work. In a final set of experiments the spin polarization of the edge channels was investigated. Here, we could make use of the advantage that HgTe quantum well structures exhibit a large Rashba spin orbit splitting. - HgTe as a 3-dimensional topological insulator is presented in chapter 3. - Chapters 4-6 serve as in depth overviews of selected works: Chapter 4 presents a detailed overview on the all electrical detection of the spin Hall effect in HgTe quantum wells. The detection of the spin polarization of the quantum spin Hall effect is shown in chapter 5 and chapter 6 gives a detailed overview on the quantum Hall effect originating from the topological surface state in strained bulk HgTe.

  20. The system SnTe-InSe

    International Nuclear Information System (INIS)

    Gurshumov, A.P.; Alidzhanov, M.A.; Aliev, A.S.; Gadzhiev, T.G.; Mamedov, N.A.

    1986-01-01

    This paper discusses the nature of the interaction and physicochemical properties of the alloys of the system SnTe-InSe. The DTA was performed on an NTR-74 pyrometer, XPA on a Dron-2.0 diffractometer and MSA on an MIM-7 metallographic microscope. The microhardness of the samples was determined on a PMT-3 microhardness tester. The congruently melting compound SnInTeSe and solid solutions based on the starting components are formed in the system

  1. The Vulcan pulse generating system

    International Nuclear Information System (INIS)

    Danson, C.N.; Edwards, C.B.; Wyatt, R.W.W.

    1985-01-01

    During the past two years several changes have been made to the front end system on the VULCAN pulse generating system. These changes give greater flexibility and a wider choice of operating conditions. This note gives an updated description of the system capabilities, and gives users of the facility an idea of the various pulse combinations that are available. (author)

  2. NMR in pulsed magnetic field

    KAUST Repository

    Abou-Hamad, Edy; Bontemps, P.; Rikken, Geert L J A

    2011-01-01

    Nuclear magnetic resonance (NMR) experiments in pulsed magnetic fields up to 30.4 T focused on 1H and 93Nb nuclei are reported. Here we discuss the advantage and limitation of pulsed field NMR and why this technique is able to become a promising research tool. © 2011 Elsevier Inc. All Rights Reserved.

  3. Progress in pulsed power fusion

    Energy Technology Data Exchange (ETDEWEB)

    Quintenz, J P; Adams, R G; Bailey, J E [Sandia Labs., Albuquerque, NM (United States); and others

    1997-12-31

    Pulsed power offers an efficient, high energy, economical source of x-rays for inertial confinement fusion (ICF) research. Two main approaches to ICF driven with pulsed power accelerators are pursued: intense light ion beams and z-pinches. Recent progress in each approach and plans for future development is described. (author). 2 figs., 10 refs.

  4. NMR in pulsed magnetic field

    KAUST Repository

    Abou-Hamad, Edy

    2011-09-01

    Nuclear magnetic resonance (NMR) experiments in pulsed magnetic fields up to 30.4 T focused on 1H and 93Nb nuclei are reported. Here we discuss the advantage and limitation of pulsed field NMR and why this technique is able to become a promising research tool. © 2011 Elsevier Inc. All Rights Reserved.

  5. A Single-Pulse Integrator

    DEFF Research Database (Denmark)

    Miller, Arne

    1974-01-01

    A single-pulse integrator is described. It gives a relative measure of the integral of the output signal from a coil monitor on the Risø 10 MeV linear accelerator, and displays the value on a digital voltmeter. The reproduccibility is found to be better than ±1% for an accelerated pulse charge...

  6. Progress in pulsed power fusion

    International Nuclear Information System (INIS)

    Quintenz, J.P.; Adams, R.G.; Bailey, J.E.

    1996-01-01

    Pulsed power offers an efficient, high energy, economical source of x-rays for inertial confinement fusion (ICF) research. Two main approaches to ICF driven with pulsed power accelerators are pursued: intense light ion beams and z-pinches. Recent progress in each approach and plans for future development is described. (author). 2 figs., 10 refs

  7. Electromagnetic pulses, localized and causal

    Science.gov (United States)

    Lekner, John

    2018-01-01

    We show that pulse solutions of the wave equation can be expressed as time Fourier superpositions of scalar monochromatic beam wave functions (solutions of the Helmholtz equation). This formulation is shown to be equivalent to Bateman's integral expression for solutions of the wave equation, for axially symmetric solutions. A closed-form one-parameter solution of the wave equation, containing no backward-propagating parts, is constructed from a beam which is the tight-focus limit of two families of beams. Application is made to transverse electric and transverse magnetic pulses, with evaluation of the energy, momentum and angular momentum for a pulse based on the general localized and causal form. Such pulses can be represented as superpositions of photons. Explicit total energy and total momentum values are given for the one-parameter closed-form pulse.

  8. A digital long pulse integrator

    International Nuclear Information System (INIS)

    Broesch, J.D.; Strait, E.J.; Snider, R.T.

    1996-10-01

    A prototype digital integrator with very long integration capabilities has been developed and field tested on an inductive magnetic sensor on the DIII-D Tokamak. The integrator is being developed for use on ITER with a pulse length of 1000 s, and has direct applications for other long pulse Tokamaks. Inductive magnetic sensors are routinely used on existing Tokamaks, are well understood, and are extremely robust, however, they require integration of the signal to determine the magnetic field strength. The next generation of Tokamaks, will have pulse lengths of 1000 s or longer, require integrators with drift and noise characteristics compatible with the very long pulse lengths. This paper will discuss the architecture, algorithms, and programming of the Long Pulse Integrator (LPI). Of particular interest are the noise control and the built-in offset correction techniques used in this application

  9. Combustion synthesis and characterization of uranium and thorium tellurides

    International Nuclear Information System (INIS)

    Czechowicz, D.G.

    1985-10-01

    This report describes an investigation of the chemical systems uranium-tellurium and thorium-tellurium. A novel synthesis technique, combustion synthesis, which uses the exothermic heat of reaction rather than externally supplied heat, was utilized to form the phases UTe, U 3 Te 4 , and UTe 2 in the U-Te system and the phases ThTe, Th 2 Te 3 , and ThTe 2 in the Th-Te system from reactions of the type U/sub x/ + Te/sub y/ = U/sub x/Te/sub y/. With this synthetic method, U-Te and Th-Te products could be formed in a matter of seconds, and the purity of the products was often greater than that of the starting materials used. Control over final product stoichiometry was found to be very difficult. The product phase distribution observed in combustion products, as determined by x-ray diffraction, electron microprobe, and optical metallographic methods, was found to be spatially complex. Lattice constants were calculated from x-ray diffraction patterns for the compounds UTe, U 3 Te 4 , and ThTe. SOLGASMIX thermodynamic equilibrium calculations were performed using available and estimated thermodynamic data on the system U-Te-O in an attempt to understand the products formed by combustion. Adiabatic combustion reaction temperatures for specific U-Te and Th-Te reactions were also calculated utilizing available and estimated thermodynamic data. 71 refs., 31 figs., 15 tabs

  10. Electrodeposition of textured Bi{sub 27}Sb{sub 28}Te{sub 45} nanowires with enhanced electrical conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Hasan, Maksudul, E-mail: maksudul.hasan@tyndall.ie [Tyndall National Institute, University College Cork, Lee Maltings, Cork (Ireland); Gautam, Devendraprakash [Tyndall National Institute, University College Cork, Lee Maltings, Cork (Ireland); Enright, Ryan [Thermal Management Research Group, Efficient Energy Transfer Department, Bell Labs Ireland, Alcatel-Lucent Ireland Ltd., Dublin (Ireland)

    2016-04-15

    This work presents the template based pulsed potential electrodeposition technique of highly textured single crystalline bismuth antimony telluride (Bi{sub 1-x}Sb{sub x}){sub 2}Te{sub 3} nanowires from a single aqueous electrolyte. Cyclic voltammetry was used as an electroanalytical tool to assess the effect of the precursor concentrations on the composition of the deposits and to determine the deposition potential for each element. Pulsed potential electrodeposition was then applied on a gold-coated anodised alumina template to examine the effect of the pulse parameters on the composition and texture of Bi{sub 27}Sb{sub 28}Te{sub 45} nanowires. The nanowires are cylindrical in shape formed during the deposition inside the porous template and highly textured as they are decorated with sparse distribution of small crystal domains. The electrical conductivity (24.1 × 10{sup 4} S m{sup −1}) of a single nanowire was measured using a four-point probe technique implemented on a custom fabricated test chip. In this work, we demonstrated that crystal orientation with respect to the transport direction controlled by tuning the pulsed electrodeposition parameters. This allowed us to realise electrical conductivities ∼2.5 times larger than Sb doped bismuth-tellurium based ternary material systems and similar to what is typically seen in binary systems. - Highlights: • Pulsed electrodeposition is described towards fabrication of (Bi{sub 1-x}Sb{sub x}){sub 2}Te{sub 3} nanowires. • The adopted method is compatible with existing CMOS process. • The nanowires were fabricated as highly textured to enhance phonon scattering. • The electrical conductivity is ∼2.5 times larger than the current ternary materials.

  11. Digital signal processing for CdTe detectors using VXIbus data collection systems

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, Daiji; Takahashi, Hiroyuki; Kurahashi, Tomohiko; Iguchi, Tetsuo; Nakazawa, Masaharu

    1996-07-01

    Recently fast signal digitizing technique has been developed, and signal waveforms with very short time periods can be obtained. In this paper, we analyzed each measured pulse which was digitized by an apparatus of this kind, and tried to improve an energy resolution of a CdTe semiconductor detector. The result of the energy resolution for {sup 137}Cs 662 keV photopeak was 13 keV. Also, we developed a fast data collection system based on VXIbus standard, and the counting rate on this system was obtained about 50 counts per second. (author)

  12. Observation of Hercules X-1 at energies above 50 TeV

    International Nuclear Information System (INIS)

    Dingus, B.L.; Chang, C.Y.; Goodman, J.A.

    1988-01-01

    A search for emission from Hercules X-1 at energies above 50 TeV during the calendar period April 1986 to July 1987 yielded two significant bursts, on UT 24 July 1986. The events during these bursts were pulsed with a period of 1.2357 s, significantly different from estimates of the contemporaneous x-ray period. The probability that this represents random statistical fluctuations of the background is estimated to be 1/70000. The muon content of the burst events is anomalous when compared with expectations from gamma-ray showers. 11 refs., 1 fig

  13. Fabrication and photocatalytic activity of high-efficiency visible-light-responsive photocatalyst ZnTe/TiO2 nanotube arrays

    International Nuclear Information System (INIS)

    Liu Yutang; Zhang Xilin; Liu Ronghua; Yang Renbin; Liu Chengbin; Cai Qingyun

    2011-01-01

    A new ZnTe modified TiO 2 nanotube (NT) array catalyst was prepared by pulse potential electrodeposition of ZnTe nanoparticles (NPs) onto TiO 2 NT arrays, and its application for photocatalytic degradation of anthracene-9-carboxylic acid (9-AnCOOH) was investigated. The even distribution of ZnTe NPs was well-proportionately grown on the top surface of the TiO 2 NT while without clogging the tube entrances. Compared with the unmodified TiO 2 NT, the ZnTe modified TiO 2 NT (ZnTe/TiO 2 NT) showed significantly enhanced photocatalytic activity towards 9-AnCOOH under simulated solar light. After 70 min of irradiation, 9-AnCOOH was degraded with the removal ratio of 45% on the bare TiO 2 NT, much lower than 80%, 90%, and 100% on the ZnTe/TiO 2 NT with the ZnTe NPs prepared under the pulsed 'on' potentials of -0.8, -1.0, and -2.0 V, respectively. The increased photodegradation efficiency mainly results from the improved photocurrent density as results of enhanced visible-light absorption and decreased hole-electron recombination due to the presence of narrow-band-gap p-type semiconductor ZnTe. -- Graphical abstract: Surface-view SEM images of ZnTe/TiO 2 NT prepared under -2.0 V, and the inset is the corresponding enlarged drawings. Display Omitted Research highlights: → A new method to deposit chalcogenides of transition metals on the TiO 2 nanotubes. → The even distribution of ZnTe nanoparticles was well-proportionedly grown onto TiO 2 NT arrays. → ZnTe/TiO 2 NT showed remarkably increased photocurrent density. → ZnTe/TiO 2 NT showed good photocatalytic performance. → The prepared new catalyst has a promising application in practical systems.

  14. Pulsed neutron generator for use with pulsed neutron activation techniques

    International Nuclear Information System (INIS)

    Rochau, G.E.

    1980-01-01

    A high-output, transportable, pulsed neutron generator has been developed by Sandia National Laboratories for use with Pulsed Neutron Activation (PNA) techniques. The PNA neutron generator generates > 10 10 14 MeV D-T neutrons in a 1.2 millisecond pulse. Each operation of the unit will produce a nominal total neutron output of 1.2 x 10 10 neutrons. The generator has been designed to be easily repaired and modified. The unit requires no additional equipment for operation or measurement of output

  15. Laser ablation comparison by picosecond pulses train and nanosecond pulse

    Science.gov (United States)

    Lednev, V. N.; Filippov, M. N.; Bunkin, A. F.; Pershin, S. M.

    2015-12-01

    A comparison of laser ablation by a train of picosecond pulses and nanosecond pulses revealed a difference in laser craters, ablation thresholds, plasma sizes and spectral line intensities. Laser ablation with a train of picosecond pulses resulted in improved crater quality while ablated mass decreased up to 30%. A reduction in laser plasma dimensions for picosecond train ablation was observed while the intensity of atomic/ionic lines in the plasma spectra was greater by a factor of 2-4 indicating an improved excitation and atomization in the plasma.

  16. Pulse on pulse: modulation and signification in Rafael Lozano-Hemmer's Pulse Room

    Directory of Open Access Journals (Sweden)

    Merete Carlson

    2012-06-01

    Full Text Available This article investigates the relation between signifying processes and non-signifying material dynamism in the installation Pulse Room (2006 by Mexican Canadian artist Rafael Lozano-Hemmer. In Pulse Room the sense of pulse is ambiguous. Biorhythms are transmitted from the pulsing energy of the visitor's beating heart to the flashing of a fragile light bulb, thereby transforming each light bulb into a register of individual life. But at the same time the flashing light bulbs together produce a chaotically flickering light environment composed by various layers of repetitive rhythms, a vibrant and pulsating “room”. Hence, the visitor in Pulse Room is invited into a complex scenario that continuously oscillates between various aspects of signification (the light bulbs representing individual lives; the pulse itself as the symbolic “rhythm of life” and instants of pure material processuality (flickering light bulbs; polyrhythmic layers. Taking our point of departure in a discussion of Gilles Deleuze's concepts of modulation and signaletic material in relation to electronic media, we examine how the complex orchestration of pulsation between signification and material modulation produces a multilayered sense of time and space that is central to the sensory experience of Pulse Room as a whole. Pulse Room is, at the very same time, a relational subject–object intimacy and an all-encompassing immersive environment modulating continuously in real space-time.

  17. Pulse shaping using a spatial light modulator

    CSIR Research Space (South Africa)

    Botha, N

    2009-07-01

    Full Text Available Femtosecond pulse shaping can be done by different kinds of pulse shapers, such as liquid crystal spatial light modulators (LC SLM), acousto optic modulators (AOM) and deformable and movable mirrors. A few applications where pulse shaping...

  18. The gyroklystron as a possible RF source for future TeV colliders

    International Nuclear Information System (INIS)

    Cheng, J.; Lawson, W.; Calame, J.P.; Latham, P.E.; Granatstein, V.L.; Reiser, M.

    1995-01-01

    At the University of Maryland we have been investigating the feasibility of using gyroklystrons as a possible RF source for the next generation of linear colliders. The preliminary sets of fundamental and second harmonic gyroklystron tube experiments have achieved a combination of pulse length, frequency and peak powers beyond the previous state of the art in RF capabilities. Production of 1 μsec pulse lengths at X and K band frequencies have shown that gyroklystrons can be a promising RF source but the achieved power levels of 30 MW still fall short of predicted requirements for future TeV colliders. An upgrade of the gyroklystron experimental facility to achieve 100 MW peak power levels will move us closer to realizing the goals for RF sources. This paper will detail the past achievements of the 30 MW system as well as modifications for the future 100 MW system. copyright 1995 American Institute of Physics

  19. Lifetime Studies of Cs2Te Cathodes at the Phin RF Photoinjector at CERN

    CERN Document Server

    Hessler, C; Divall Csatari, M; Doebert, S; Fedosseev, V

    2012-01-01

    The PHIN photoinjector has been developed to study the feasibility of a photoinjector option for the CLIC (Compact LInear Collider) drive beam as an alternative to the baseline design, using a thermionic gun. The CLIC drive beam requires a high charge of 8.4 nC per bunch in 0.14 ms long trains, with 2 ns bunch spacing and 50 Hz macro pulse repetition rate, which corresponds to a total charge per macro pulse of 0.59 mC. This means unusually high peak and average currents for photoinjectors and is challenging concerning the cathode lifetime. In this paper detailed studies of the lifetime of Cs2Te cathodes, produced by the co-evaporation technique, are presented with respect to bunch charge, train length and vacuum level. Furthermore, the impact of the train length and bunch charge on the vacuum level will be discussed and steps to extend the lifetime will be outlined.

  20. MoSbTe for high-speed and high-thermal-stability phase-change memory applications

    Science.gov (United States)

    Liu, Wanliang; Wu, Liangcai; Li, Tao; Song, Zhitang; Shi, Jianjun; Zhang, Jing; Feng, Songlin

    2018-04-01

    Mo-doped Sb1.8Te materials and electrical devices were investigated for high-thermal-stability and high-speed phase-change memory applications. The crystallization temperature (t c = 185 °C) and 10-year data retention (t 10-year = 112 °C) were greatly enhanced compared with those of Ge2Sb2Te5 (t c = 150 °C, t 10-year = 85 °C) and pure Sb1.8Te (t c = 166 °C, t 10-year = 74 °C). X-ray diffraction and transmission electron microscopy results show that the Mo dopant suppresses crystallization, reducing the crystalline grain size. Mo2.0(Sb1.8Te)98.0-based devices were fabricated to evaluate the reversible phase transition properties. SET/RESET with a large operation window can be realized using a 10 ns pulse, which is considerably better than that required for Ge2Sb2Te5 (∼50 ns). Furthermore, ∼1 × 106 switching cycles were achieved.

  1. Surface passivation of HgCdTe by CdZnTe and its characteristics

    Science.gov (United States)

    Lee, T. S.; Choi, K. K.; Jeoung, Y. T.; Kim, H. K.; Kim, J. M.; Kim, Y. H.; Chang, J. M.; Song, W. S.; Kim, S. U.; Park, M. J.; Lee, S. D.

    1997-06-01

    In this paper, we report the results of capacitance-voltage measurements conducted on several metal-insulator semiconductor (MIS) capacitors in which HgCdTe surfaces are treated with various surface etching and oxidation processes. CdZnTe passivation layers were deposited on HgCdTe surfaces by thermal evaporation after the surfaces were etched with 0.5-2.0% bromine in methanol solution, or thin oxide layers (tox ˜ few ten Å) were grown on the surfaces, in order to investigate effects of the surface treatments on the electrical properties of the surfaces, as determined from capacitance-voltage (C-V) measurements at 80K and 1 MHz. A negative flat band voltage has been observed for MIS capacitors fabricated after etching of HgCdTe surfaces with bromine in methanol solutions, which is reported to make the surface Te-rich. It is inferred that residual Te on the surface is a positive charge, Te4+. C-V characteristics for MIS capacitors fabricated on oxide surfaces grown by air-exposure and electrolytic process have shown large hysteresis effects, from which it is inferred that imperfect and electrically active oxide compounds and HgTe particles near the surface become slow interface states.

  2. Om te staak of nie te staak nie? Die sieninge van 'n aantal swart ...

    African Journals Online (AJOL)

    Erna Kinsey

    sig, is eerstens om ondersoek in te stel na 'n groep swart opvoeders se sieninge oor opvoeders se reg om te staak. Tweedens sal na die redes wat hierdie opvoeders aanvoer waarom hulle al aan stakings deel- geneem het of sal deelneem, gelet word. Derdens sal die redes waarom sommige opvoeders nie sal staak nie, ...

  3. The fingerprint of Te-rich and stoichiometric Bi2Te3 nanowires by Raman spectroscopy

    Science.gov (United States)

    Rodríguez-Fernández, Carlos; Manzano, Cristina V.; Romero, Aldo H.; Martín, Jaime; Martín-González, Marisol; Morais de Lima, Mauricio, Jr.; Cantarero, Andrés

    2016-02-01

    We unambiguously show that the signature of Te-rich bismuth telluride is the appearance of three new peaks in the Raman spectra of Bi2Te3, located at 88, 117 and 137 cm-1. For this purpose, we have grown stoichiometric Bi2Te3 nanowires as well as Te-rich nanowires. The absence of these peaks in stoichiometric nanowires, even in those with the smallest diameter, shows that they are not related to confinement effects or the lack of inversion symmetry, as stated in the literature, but to the existence of Te clusters. These Te clusters have been found in non-stoichiometric samples by high resolution electron microscopy, while they are absent in stoichiometric samples. The Raman spectra of the latter corresponds to the one for bulk Bi2Te3. The intensity of these Raman peaks are clearly correlated to the Te content. In order to ensure statistically meaningful results, we have investigated several regions from every sample.

  4. Cumulative effects of Te precipitates in CdZnTe radiation detectors

    International Nuclear Information System (INIS)

    Bolotnikov, A.E.; Camarda, G.S.; Carini, G.A.; Cui, Y.; Li, L.; James, R.B.

    2007-01-01

    High-quality radiation detector-grade CdZnTe material is free from large-scale defects, such as grain boundaries, twins, and large Te or Cd inclusions (>50 μm), although it usually contains high concentrations of uniformly distributed Te inclusions and precipitates, typically of ∼20-μm-diameter size or smaller. We address the effects of the small-size Te precipitates on charge collection in CZT detectors, the significance of which is not yet well characterized. The strong correlation that we earlier found between the high-resolution X-ray maps and IR images proved that even small Te precipitates can trap substantial fractions of charge from the electron cloud. In this work, we modeled the transport of an electron cloud across idealized CZT devices containing Te precipitates to demonstrate that their cumulative effect can explain the degradation of energy resolution and the detection efficiency losses observed in actual CZT devices. Due to lack of experimental data on how the Te precipitates interact with an electron cloud, we developed a simplified (phenomenological) model based on the geometrical aspects of the problem. Despite its simplicity, the model correctly reproduced many experimental facts and gave quantitative predictions on the extent to which the presence of Te precipitates and inclusions can be tolerated. The broadening of the electron cloud due to repulsion and diffusion is at the core of the problem, making even low concentrations of small precipitates important in the device's performance

  5. Bomb pulse biology

    Energy Technology Data Exchange (ETDEWEB)

    Falso, Miranda J. Sarachine [Center for Accelerator Mass Spectrometry, Mail Stop L-397, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551 (United States); Buchholz, Bruce A., E-mail: buchholz2@llnl.gov [Center for Accelerator Mass Spectrometry, Mail Stop L-397, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551 (United States)

    2013-01-15

    The past decade has seen an explosion in use of the {sup 14}C bomb pulse to do fundamental cell biology. Studies in the 1960s used decay counting to measure tissue turnover when the atmospheric {sup 14}C/C concentration was changing rapidly. Today bulk tissue measurements are of marginal interest since most of the carbon in the tissue resides in proteins, lipids and carbohydrates that turn over rapidly. Specific cell types with specialized functions are the focus of cell turnover investigations. Tissue samples need to be fresh or frozen. Fixed or preserved samples contain petroleum-derived carbon that has not been successfully removed. Cell or nuclear surface markers are used to sort specific cell types, typically by fluorescence-activated cell sorting (FACS). Specific biomolecules need to be isolated with high purity and accelerator mass spectrometry (AMS) measurements must accommodate samples that generally contain less than 40 {mu}g of carbon. Furthermore, all separations must not add carbon to the sample. Independent means such as UV absorbance must be used to confirm molecule purity. Approaches for separating specific proteins and DNA and combating contamination of undesired molecules are described.

  6. Pulsed radiation decay logging

    International Nuclear Information System (INIS)

    Mills, W.R. Jr.

    1983-01-01

    There are provided new and improved well logging processes and systems wherein the detection of secondary radiation is accomplished during a plurality of time windows in a manner to accurately characterize the decay rate of the secondary radiation. The system comprises a well logging tool having a primary pulsed radiation source which emits repetitive time-spaced bursts of primary radiation and detector means for detecting secondary radiation resulting from the primary radiation and producing output signals in response to the detected radiation. A plurality of measuring channels are provided, each of which produces a count rate function representative of signals received from the detector means during successive time windows occurring between the primary radiation bursts. The logging system further comprises means responsive to the measuring channels for producing a plurality of functions representative of the ratios of the radiation count rates measured during adjacent pairs of the time windows. Comparator means function to compare the ratio functions and select at least one of the ratio functions to generate a signal representative of the decay rate of the secondary radiation

  7. NEMP (Nuclear Electromagnetic Pulse)

    International Nuclear Information System (INIS)

    Grunow, H.K.

    The variety of measures discussed in this contribution can be used to achieve with minimum effort a damping of 10 6 :1 (120 dB) between the interfering pulses in the networks and lines outside the buildings and the lines leading to the semiconductors. Expert knowledge, experience, and insight into the systems are required to solve this task optimally. The procedure to be adopted for NEMP protection differs only slightly from that used for achieving electromagnetic compatibility and lightning protection. Industry has developed the equipment for overvoltage protection and offers graded protection systems, experienced experts and systems engineers are available. This potential of the industry could be used to sponsor a pilot project, e.g. by public research funds. One of the goals of such a project could be to work out reliable data for cost estimated for large projects. Even if one would not accept the hypothetical probability of a nuclear war as a reason good anough to start such a project, it would not be justified to deny the necessity of additional expenditure for setting up a ''NEMP emergency system'' for protection waterborne traffic on purely financial grounds. (orig./RW) [de

  8. Pulse number control of electrical resistance for multi-level storage based on phase change

    International Nuclear Information System (INIS)

    Nakayama, K; Takata, M; Kasai, T; Kitagawa, A; Akita, J

    2007-01-01

    Phase change nonvolatile memory devices composed of SeSbTe chalcogenide semiconductor thin film were fabricated. The resistivity of the SeSbTe system was investigated to apply to multi-level data storage. The chalcogenide semiconductor acts as a programmable resistor that has a large dynamic range. The resistance of the chalcogenide semiconductor can be set to intermediate resistances between the amorphous and crystalline states using electric pulses of a specified power, and it can be controlled by repetition of the electric pulses. The size of the memory cell used in this work is 200 nm thick with a contact area of 1 μm diameter. The resistance of the chalcogenide semiconductor gradually varies from 41 kΩ to 840 Ω within octal steps. The resistance of the chalcogenide semiconductor decreases with increasing number of applied pulses. The step-down characteristic of the resistance can be explained as the crystalline region of the active phase change region increases with increasing number of applied pulses. The extent of crystallization was also estimated by the overall resistivity of the active region of the memory cell

  9. Study of Te Inclusion and Related Point Defects in THM-Growth CdMnTe Crystal

    Science.gov (United States)

    Mao, Yifei; Zhang, Jijun; Min, Jiahua; Liang, Xiaoyan; Huang, Jian; Tang, Ke; Ling, Liwen; Li, Ming; Zhang, Ying; Wang, Linjun

    2018-02-01

    This study establishes a model for describing the interaction between Te inclusions, dislocations and point defects in CdMnTe crystals. The role of the complex environment surrounding the formation of Te inclusions was analyzed. Images of Te inclusions captured by scanning electron microscope and infrared microscope were used to observe the morphology of Te inclusions. The morphology of Te inclusions is discussed in light of crystallography, from the crystal growth temperature at 900°C to the melting temperature of Te inclusions using the traveling heater method. The dislocation nets around Te inclusions were calculated by counting lattice mismatches between the Te inclusions and the bulk CdMnTe at 470°C. The point defects of Te antisites were found to be gathered around Te inclusions, with dislocation climb during the cooling phase of crystal growth from 470°C to room temperature. The Te inclusions, dislocation nets and surrounding point defects are considered to be an entirety for evaluating the effect of Te inclusions on CdMnTe detector performance, and an effective mobility-lifetime product (μτ) was obtained.

  10. Magnetic Alignment of Pulsed Solenoids Using the Pulsed Wire Method

    International Nuclear Information System (INIS)

    Arbelaez, D.; Madur, A.; Lipton, T.M.; Waldron, W.L.; Kwan, J.W.

    2011-01-01

    A unique application of the pulsed-wire measurement method has been implemented for alignment of 2.5 T pulsed solenoid magnets. The magnetic axis measurement has been shown to have a resolution of better than 25 (micro)m. The accuracy of the technique allows for the identification of inherent field errors due to, for example, the winding layer transitions and the current leads. The alignment system is developed for the induction accelerator NDCX-II under construction at LBNL, an upgraded Neutralized Drift Compression experiment for research on warm dense matter and heavy ion fusion. Precise alignment is essential for NDCX-II, since the ion beam has a large energy spread associated with the rapid pulse compression such that misalignments lead to corkscrew deformation of the beam and reduced intensity at focus. The ability to align the magnetic axis of the pulsed solenoids to within 100 pm of the induction cell axis has been demonstrated.

  11. Energy relaxation in IR laser excited Hg1-xCdxTe

    International Nuclear Information System (INIS)

    Storebo, A K; Brudevoll, T; Olsen, O; Norum, O C; Breivik, M

    2009-01-01

    IR laser excitation of Hg l-x Cd x Te by low-fluence femtosecond and high fluence microsecond pulses was explored for the technologically important alloy fractions x ∼ 0.2 and x ∼ 0.28. We have used first principles (LAPW) electronic structure calculations and finite element modelling, supported by Monte Carlo simulation for the description of femtosecond pulse carrier relaxation and the transport parameters. Laser wavelengths considered were 6.4 - 10.6 μm for x ∼ 0.2 and 3.8 - 4.8 μm for x ∼ 0.28, with an incident 1 microsecond pulse fluence of 2 J/cm 2 . Many energy transfer mechanisms are invoked due to the long timescales of the microsecond pulses, and a main challenge is therefore to elucidate how these interplay in situations away from thermal equilibrium. Mechanisms studied include one- and two-photon absorption (OPA and TPA) across the band gap, inter-valence band absorption (IVA) between light- and heavy hole bands, electron-hole recombination/impact ionization, band gap renormalisation, intra-band free carrier absorption (FCA), excess carrier temperatures, non-equilibrium phonon generation, and refractive index changes. In the high fluence case, lattice temperatures evolve considerably during the laser pulse in response to the heated carriers. The chosen photon energies lie just above the band gap at the starting lattice temperature of 77 K, and nonlinear effects therefore dominate as the material heats up and the band gap begins to exceed the photon energy. Because of the low photon energy we must rely on Auger recombination, inter-valence band absorption and free carrier absorption to heat the carrier plasma. Although some Hg l-x Cd x Te material parameters are now relatively well known, existing data for many of the processes are inadequate for cases far away from thermal equilibrium. Furthermore, the role of Auger recombination in relation to non-intrinsic recombination has been a matter of debate lately. In this respect, information from

  12. Pulsed ultrasonic stir welding method

    Science.gov (United States)

    Ding, R. Jeffrey (Inventor)

    2013-01-01

    A method of performing ultrasonic stir welding uses a welding head assembly to include a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. In the method, the rod is rotated about its longitudinal axis during a welding operation. During the welding operation, a series of on-off ultrasonic pulses are applied to the rod such that they propagate parallel to the rod's longitudinal axis. At least a pulse rate associated with the on-off ultrasonic pulses is controlled.

  13. Pulse timing for cataclysmic variables

    International Nuclear Information System (INIS)

    Chester, T.J.

    1979-01-01

    It is shown that present pulse timing measurements of cataclysmic variables can be explained by models of accretion disks in these systems, and thus such measurements can constrain disk models. The model for DQ Her correctly predicts the amplitude variation of the continuum pulsation and can also perhaps explain the asymmetric amplitude of the pulsed lambda4686 emission line. Several other predictions can be made from the model. In particular, if pulse timing measurements that resolve emission lines both in wavelength and in binary phase can be made, the projected orbital radius of the white dwarf could be deduced

  14. Fabrication of Te and Te-Au Nanowires-Based Carbon Fiber Fabrics for Antibacterial Applications

    Directory of Open Access Journals (Sweden)

    Ting-Mao Chou

    2016-02-01

    Full Text Available Pathogenic bacteria that give rise to diseases every year remain a major health concern. In recent years, tellurium-based nanomaterials have been approved as new and efficient antibacterial agents. In this paper, we developed the approach to directly grow tellurium nanowires (Te NWs onto commercial carbon fiber fabrics and demonstrated their antibacterial activity. Those Te NWs can serve as templates and reducing agents for gold nanoparticles (Au NPs to deposit. Three different Te-Au NWs with varied concentration of Au NPs were synthesized and showed superior antibacterial activity and biocompability. These results indicate that the as-prepared carbon fiber fabrics with Te and Te-Au NWs can become antimicrobial clothing products in the near future.

  15. Hyper dispersion pulse compressor for chirped pulse amplification systems

    Science.gov (United States)

    Barty, Christopher P. J.

    2011-11-29

    A grating pulse compressor configuration is introduced for increasing the optical dispersion for a given footprint and to make practical the application for chirped pulse amplification (CPA) to quasi-narrow bandwidth materials, such as Nd:YAG. The grating configurations often use cascaded pairs of gratings to increase angular dispersion an order of magnitude or more. Increased angular dispersion allows for decreased grating separation and a smaller compressor footprint.

  16. Improved structural and electrical properties in native Sb2Te3/GexSb2Te3+x van der Waals superlattices due to intermixing mitigation

    NARCIS (Netherlands)

    Cecchi, Stefano; Zallo, Eugenio; Momand, Jamo; Wang, Ruining; Kooi, Bart J.; Verheijen, Marcel A.; Calarco, Raffaella

    Superlattices made of Sb2Te3/GeTe phase change materials have demonstrated outstanding performance with respect to GeSbTe alloys in memory applications. Recently, epitaxial Sb2Te3/GeTe superlattices were found to feature GexSb2Te3+x blocks as a result of intermixing between constituting layers.

  17. Improved structural and electrical properties in native Sb2Te3/GexSb2Te3+x van der Waals superlattices due to intermixing mitigation

    NARCIS (Netherlands)

    Cecchi, S.; Zallo, E.; Momand, J.; Wang, R.; Kooi, B.J.; Verheijen, M.A.; Calarco, R.

    Superlattices made of Sb2Te3/GeTe phase change materials have demonstrated outstanding performance with respect to GeSbTe alloys in memory applications. Recently, epitaxial Sb2Te3/GeTe superlattices were found to feature GexSb2Te3+x blocks as a result of intermixing between constituting layers. Here

  18. Design principles for HgTe based topological insulator devices

    Science.gov (United States)

    Sengupta, Parijat; Kubis, Tillmann; Tan, Yaohua; Povolotskyi, Michael; Klimeck, Gerhard

    2013-07-01

    The topological insulator properties of CdTe/HgTe/CdTe quantum wells are theoretically studied. The CdTe/HgTe/CdTe quantum well behaves as a topological insulator beyond a critical well width dimension. It is shown that if the barrier (CdTe) and well-region (HgTe) are altered by replacing them with the alloy CdxHg1-xTe of various stoichiometries, the critical width can be changed. The critical quantum well width is shown to depend on temperature, applied stress, growth directions, and external electric fields. Based on these results, a novel device concept is proposed that allows to switch between a normal semiconducting and topological insulator state through application of moderate external electric fields.

  19. Investigations on the system Te/O/Br

    International Nuclear Information System (INIS)

    Oppermann, H.; Kunze, G.; Wolf, E.; Titov, V.A.; Kokovin, G.A.

    1978-01-01

    The melting point diagram of the system TeBr 4 -TeO 2 was obtained by total pressure measurements and DTA measurements. A congruent melting composition Te 6 O 11 Br 2 exists, the melting point is 570 0 C. The enthalpy of formation and the standard entropy of the species TeOBr 2 ,g was derived from measurements of the total pressure over Te 6 O 11 Br 2 /TeBr 4 and from the transport behaviour of the TeO 2 with Br 2 . From the decomposition-pressure measurements over Te 6 O 11 Br 2 /TeO 2 follow the partial pressures. The enthalpy of formation ΔH 0 (Te 6 O 11 Br 2 ,f,298) -453.5 kcal/Mol was obtained from the enthalpy of solution. The transport-behaviour of TeO 2 with HBr, TeBr 4 and Br 2 and that of Te 6 O 11 Br 2 is clear with the thermodynamic data of TeOBr 2 . (author)

  20. A Linux cluster for between-pulse magnetic equilibrium reconstructions and other processor bound analyses

    International Nuclear Information System (INIS)

    Peng, Q.; Groebner, R. J.; Lao, L. L.; Schachter, J.; Schissel, D. P.; Wade, M. R.

    2001-01-01

    A 12-processor Linux PC cluster has been installed to perform between-pulse magnetic equilibrium reconstructions during tokamak operations using the EFIT code written in FORTRAN. The MPICH package implementing message passing interface is employed by EFIT for data distribution and communication. The new system calculates equilibria eight times faster than the previous system yielding a complete equilibrium time history on a 25 ms time scale 4 min after the pulse ends. A graphical interface is provided for users to control the time resolution and the type of EFITs. The next analysis to benefit from the cluster is CERQUICK written in IDL for ion temperature profile analysis. The plan is to expand the cluster so that a full profile analysis (Te, Ti, ne, Vr, Zeff) can be made available between pulses, which lays the ground work for Kinetic EFIT and/or ONETWO power balance analyses

  1. Review of CdTe medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Entine, G; Garcia, D A; Tow, D E

    1977-02-01

    CdTe sensors are now being used in several areas of nuclear medicine. CdTe probe technics, originally developed to study dental pathology in dog models, are being used clinically to diagnose venous thrombosis of the legs and to detect occult dental infections in patients scheduled for prosthetic cardiovascular and orthopedic surgery. Similar instrumentation is in use in animal research of myocardial infarction and synthetic tooth substitutes. Transmission technics have also been developed to diagnose pulmonary edema and to measure bone mineral changes in space flight. Investigations are also underway in the use of linear or two-dimensional arrays of CdTe gamma sensors for medical imaging. Economic considerations have slowed this work, but the technology appears to be available. Development of photoconductive CdTe X-ray detectors for scintigraphic scanners has also begun. Rapid detector improvement will be needed for success in this field, but the potential usefulness is very great. Together, the present application results are encouraging and wide use of CdTe detectors should occur within only a few years.

  2. Research into the electrical property variation of undoped CdTe and ZnTe crystals grown under Te-rich conditions

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yadong, E-mail: xyd220@nwpu.edu.cn; Liu, Hang; He, Yihui; Yang, Rui; Luo, Lin; Jie, Wanqi

    2014-11-05

    Highlights: • Conductivity type and resistivity of undoped Te-rich ZnTe and CdTe are different. • Te{sub i} and V{sub Zn} as the dominant defects account for the p-type low resistivity ZnTe. • Te{sub Cd} as the principle defect leading to the light n-type high resistivity CdTe. • DAP and eA peaks dominate the luminescence with their intensities anti-correlated. - Abstract: Both undoped ZnTe and CdTe bulk single crystals are grown under Te-saturated conditions from the solution and melt, respectively. To give an insight into the variation of the electrical properties, the defects structures in both tellurides are discussed. According to the actual growth velocities and the entire cooling history, tellurium interstitials (Te{sub i}) and Zinc vacancies (V{sub Zn}) are proposed as the dominant grown-in defects, account for the low resistivity of p-type ZnTe. However, relatively high pulling rates and slow cooling-down processes result in tellurium anti-sites (Te{sub Cd}) as the principle grown-in defects, leading to the high resistivity of light n-type CdTe. Further low-temperature (8.6 K) photoluminescence spectra of both tellurides are obtained. The donor–acceptor pair (DAP) and recombination of free electron to neutral acceptor (eA) dominate the luminescence, however, with their intensities are anti-correlated. eA is superior to DAP in undoped Te-rich ZnTe, suggests a high concentration of Te{sub i} or V{sub Zn}. On the contrary, DAP is the principal emission for undoped Te-rich CdTe. In addition, V-line is clearly identified in undoped Te-rich ZnTe, which possibly associated with V{sub Zn} or close Frenkel pair V{sub Zn}–Zn{sub i}.

  3. Harmonic generation with a dual frequency pulse.

    Science.gov (United States)

    Keravnou, Christina P; Averkiou, Michalakis A

    2014-05-01

    Nonlinear imaging was implemented in commercial ultrasound systems over the last 15 years offering major advantages in many clinical applications. In this work, pulsing schemes coupled with a dual frequency pulse are presented. The pulsing schemes considered were pulse inversion, power modulation, and power modulated pulse inversion. The pulse contains a fundamental frequency f and a specified amount of its second harmonic 2f. The advantages and limitations of this method were evaluated with both acoustic measurements of harmonic generation and theoretical simulations based on the KZK equation. The use of two frequencies in a pulse results in the generation of the sum and difference frequency components in addition to the other harmonic components. While with single frequency pulses, only power modulation and power modulated pulse inversion contained odd harmonic components, with the dual frequency pulse, pulse inversion now also contains odd harmonic components.

  4. Pulsed Corona for Sustainable Technology

    International Nuclear Information System (INIS)

    Heesch, E.J.M. van; Pemen, A.J.M.; Yan, K.; Blom, P.P.M.; Huijbrechts, P.A.H.J.; Der Laan, P.C.T. van

    2000-01-01

    Highly active coronas with a peak power of up to 25 MW p/m corona wire and kJ/liter energy densities in the streamer channels can be produced by pulsed power. Since the voltage pulses are short, full breakdown does not occur even though the discharge currents are hundreds of Amperes. A matched pulsed power source can deposit up to 80% of its electrical energy into such a controlled discharge. Reliable and efficient sources characterized by 100 kV,150 ns wide pulses at 1000 Hz have passed 400 hours of operation. The area of applications is growing: VOC control, hot gas cleanup, water and air purification and sterilization. (author)

  5. Next generation Chirped Pulse Amplification

    Energy Technology Data Exchange (ETDEWEB)

    Nees, J; Biswal, S; Mourou, G [Univ. Michigan, Center for Ultrafast Optical Science, Ann Arbor, MI (United States); Nishimura, Akihiko; Takuma, Hiroshi

    1998-03-01

    The limiting factors of Chirped Pulse Amplification (CPA) are discussed and experimental results of CPA in Yb:glass regenerative amplifier are given. Scaling of Yb:glass to the petawatt level is briefly discussed. (author)

  6. Pulsed ventilation in mines. II

    Energy Technology Data Exchange (ETDEWEB)

    Krause, D

    1975-06-01

    Using test results, an attempt is made to determine the form of the free jet and to derive design data for pulsed fans. The most suitable placing of these fans for the ventilation of headings is discussed.

  7. Quantitative pulsed eddy current analysis

    International Nuclear Information System (INIS)

    Morris, R.A.

    1975-01-01

    The potential of pulsed eddy current testing for furnishing more information than conventional single-frequency eddy current methods has been known for some time. However, a fundamental problem has been analyzing the pulse shape with sufficient precision to produce accurate quantitative results. Accordingly, the primary goal of this investigation was to: demonstrate ways of digitizing the short pulses encountered in PEC testing, and to develop empirical analysis techniques that would predict some of the parameters (e.g., depth) of simple types of defect. This report describes a digitizing technique using a computer and either a conventional nuclear ADC or a fast transient analyzer; the computer software used to collect and analyze pulses; and some of the results obtained. (U.S.)

  8. Pulsed high-power beams

    International Nuclear Information System (INIS)

    Reginato, L.L.; Birx, D.L.

    1988-01-01

    The marriage of induction linac technology with nonlinear magnetic modulators has produced some unique capabilities. It is now possible to produce short-pulse electron beams with average currents measured in amperes, at gradients approaching 1-MeV/m, and with power efficiencies exceeding 50%. This paper reports on a 70-MeV, 3-kA induction accelerator (ETA II) constructed at the Lawrence Livermore National Laboratory that incorporates the pulse technology concepts that have evolved over the past several years. The ETA II is a linear induction accelerator and provides a test facility for demonstration of the high-average-power components and high-brightness sources used in such accelerators. The pulse drive of the accelerator is based on state-of-the-art magnetic pulse compressors with very high peak-power capability, repetition rates exceeding 1 kHz, and excellent reliability

  9. Pulsed ultrasonic stir welding system

    Science.gov (United States)

    Ding, R. Jeffrey (Inventor)

    2013-01-01

    An ultrasonic stir welding system includes a welding head assembly having a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. During a welding operation, ultrasonic pulses are applied to the rod as it rotates about its longitudinal axis. The ultrasonic pulses are applied in such a way that they propagate parallel to the longitudinal axis of the rod.

  10. Pulsed feedback defers cellular differentiation.

    Directory of Open Access Journals (Sweden)

    Joe H Levine

    2012-01-01

    Full Text Available Environmental signals induce diverse cellular differentiation programs. In certain systems, cells defer differentiation for extended time periods after the signal appears, proliferating through multiple rounds of cell division before committing to a new fate. How can cells set a deferral time much longer than the cell cycle? Here we study Bacillus subtilis cells that respond to sudden nutrient limitation with multiple rounds of growth and division before differentiating into spores. A well-characterized genetic circuit controls the concentration and phosphorylation of the master regulator Spo0A, which rises to a critical concentration to initiate sporulation. However, it remains unclear how this circuit enables cells to defer sporulation for multiple cell cycles. Using quantitative time-lapse fluorescence microscopy of Spo0A dynamics in individual cells, we observed pulses of Spo0A phosphorylation at a characteristic cell cycle phase. Pulse amplitudes grew systematically and cell-autonomously over multiple cell cycles leading up to sporulation. This pulse growth required a key positive feedback loop involving the sporulation kinases, without which the deferral of sporulation became ultrasensitive to kinase expression. Thus, deferral is controlled by a pulsed positive feedback loop in which kinase expression is activated by pulses of Spo0A phosphorylation. This pulsed positive feedback architecture provides a more robust mechanism for setting deferral times than constitutive kinase expression. Finally, using mathematical modeling, we show how pulsing and time delays together enable "polyphasic" positive feedback, in which different parts of a feedback loop are active at different times. Polyphasic feedback can enable more accurate tuning of long deferral times. Together, these results suggest that Bacillus subtilis uses a pulsed positive feedback loop to implement a "timer" that operates over timescales much longer than a cell cycle.

  11. Artistic Representation with Pulsed Holography

    International Nuclear Information System (INIS)

    Ishii, S

    2013-01-01

    This thesis describes artistic representation through pulsed holography. One of the prevalent practical problems in making holograms is object movement. Any movement of the object or film, including movement caused by acoustic vibration, has the same fatal results. One way of reducing the chance of movement is by ensuring that the exposure is very quick; using a pulsed laser can fulfill this objective. The attractiveness of using pulsed laser is based on the variety of materials or objects that can be recorded (e.g., liquid material or instantaneous scene of a moving object). One of the most interesting points about pulsed holograms is that some reconstructed images present us with completely different views of the real world. For example, the holographic image of liquid material does not appear fluid; it looks like a piece of hard glass that would produce a sharp sound upon tapping. In everyday life, we are unfamiliar with such an instantaneous scene. On the other hand, soft-textured materials such as a feather or wool differ from liquids when observed through holography. Using a pulsed hologram, we can sense the soft touch of the object or material with the help of realistic three-dimensional (3-D) images. The images allow us to realize the sense of touch in a way that resembles touching real objects. I had the opportunity to use a pulsed ruby laser soon after I started to work in the field of holography in 1979. Since then, I have made pulsed holograms of activities, including pouring water, breaking eggs, blowing soap bubbles, and scattering feathers and popcorn. I have also created holographic art with materials and objects, such as silk fiber, fabric, balloons, glass, flowers, and even the human body. Whenever I create art, I like to present the spectator with a new experience in perception. Therefore, I would like to introduce my experimental artwork through those pulsed holograms.

  12. Anomalous phase change characteristics in Fe-Te materials

    International Nuclear Information System (INIS)

    Fu, X. T.; Song, W. D.; Ji, R.; Ho, H. W.; Wang, L.; Hong, M. H.

    2012-01-01

    Phase change materials have become significantly attractive due to its unique characteristics for its extensive applications. In this paper, a kind of phase change material, which consists of Fe and Te components, is developed. The crystallization temperature of the Fe-Te materials is 180 deg. C for Fe 1.19 Te and can be adjusted by the Fe/Te ratio. High-speed phase change in the Fe-Te materials has been demonstrated by nanosecond laser irradiation. Comparing to conventional phase change materials, the Fe-Te materials exhibit an anomalous optical property that has higher reflectivity at amorphous than crystalline state, which is useful for data storage design.

  13. Simple one-pot aqueous synthesis of CdHgTe nanocrystals using sodium tellurite as the Te source

    International Nuclear Information System (INIS)

    Shen, Zhitao; Luo, Chunhua; Huang, Rong; Wang, Yiting; Peng, Hui; Travas-sejdic, Jadranka

    2014-01-01

    In this work, we systematically investigated the one-pot aqueous synthesis conditions of CdHgTe nanocrystals (NCs) using sodium tellurite (Na 2 TeO 3 ) as the Te source, and found that the added content of Hg 2+ and the initial pH value of reaction solutions significantly affected the photoluminescence quantum yield (PL QY) of alloyed CdHgTe NCs. When the concentration of Cd was 1.0 mmol L −1 , the mole ratio of Cd/Te/Hg/MPA was 1:0.5:0.05:2.4, and the initial pH value of the reaction solution was about 8.78, the PL QY of as-prepared CdHgTe NCs was up to 45%. Characterization by HRTEM and XRD confirmed the crystalline nature of CdHgTe NCs. Compared to other synthetic approaches of CdHgTe NCs, our experimental results indicate that Na 2 TeO 3 could be an attractive alternative Te source to directly synthesize CdHgTe NCs in aqueous media. - Highlights: • A one-pot method was developed for the synthesis of highly luminescent CdHgTe nanocrystals (NCs). • Sodium tellurite was used as the Te source. • The quantum yield reached up to 45%. • The experimental conditions were optimized and the prepared CdHgTe NCs were characterized

  14. TeV gamma-ray astronomy

    International Nuclear Information System (INIS)

    Cui Wei

    2009-01-01

    The field of ground-based gamma-ray astronomy has enjoyed rapid growth in recent years. As an increasing number of sources are detected at TeV energies, the field has matured and become a viable branch of modern astronomy. Lying at the uppermost end of the electromagnetic rainbow, TeV photons are always preciously few in number but carry essential information about the particle acceleration and radiative processes involved in extreme astronomical settings. Together with observations at longer wavelengths, TeV gamma-ray observations have drastically improved our view of the universe. In this review, we briefly describe recent progress in the field. We will conclude by providing a personal perspective on the future of the field, in particular, on the significant roles that China could play in advancing this young but exciting field. (invited reviews)

  15. The Toulouse pulsed magnet facility

    International Nuclear Information System (INIS)

    2006-01-01

    The 'Laboratoire National des Champs Magnetiques Pulses' (LNCMP) is an international user facility providing access to pulsed magnetic fields up to and beyond 60 T. The laboratory disposes of 10 magnet stations equipped with long-pulse magnets operating in the 35-60 T range and a short-pulse system reaching magnetic fields in excess of 70 T. The experimental infrastructure includes various high and low-temperature systems ranging from ordinary flow-type cryostats to dilution refrigerators reaching 50 mK, as well as different types of high-pressure cells. Experimental techniques include magnetization, transport, luminescence, IR-spectroscopy and polarimetry. The LNCMP pursues an extensive in-house research program focussing on all technological and scientific aspects of pulsed magnetic fields. Recent technical developments include the implementation of 60 T rapid-cooling coils, an 80 T prototype, a pulsed dipole magnet for optical investigations of dilute matter and a transportable horizontal access magnet for small angle x-ray scattering experiments. Scientific activities cover a variety of domains, including correlated electron systems, magnetism, semiconductors and nanoscience

  16. Delineation of phase fields at the Te-rich end of the Ru Te binary system

    Science.gov (United States)

    Ali (Basu), M.; Bharadwaj, S. R.; Das, D.

    2005-04-01

    The tellurium rich side of the ruthenium-tellurium binary system was studied by differential thermal analysis. To avoid reported problems of Te loss by evaporation and reactive interference of Te to the thermocouples of the thermal analyzer, the present study made use of specially designed sealed quartz capsules as DTA containers. The thermal analyses were carried out over the compositional range of 0.66 ⩽ xTe ⩽ 1.00 with the help of SETARAM TG/DTA and other indigenously built thermal analyzers available in this laboratory. The thermal data generated for fifteen different compositions were interpreted for the nature of phase transitions occurring at their characteristic temperatures. The Ru-Te binary system was found to have a eutectic transformation at 444 °C at a composition of xTe = 0.918 and a monotectic transformation at 447 °C at a composition of xTe = 0.700. Up to 6 at.% Ru is soluble in Te at about 440 °C.

  17. TeV. The dream energy scale

    International Nuclear Information System (INIS)

    Murayama, Hitoshi

    2006-01-01

    In this talk, I'd like to explain why the TeV, 1,000,000,000,00 electron volt, is a particularly interesting energy scale in physics. I being recapitulating what particle physics is all about, citing two big questions: what the Universe is made of, and Einstein's dream of unification. TeV energy appears to be relevant to both questions, suggesting rich and complex physics at this energy. I outline how two facilities, LHC and ILC, will work together with reveal what is going on at this exciting energy scale. (author)

  18. PbSnTe injection lasers

    International Nuclear Information System (INIS)

    Oron, M.

    1982-03-01

    Carrier confined homostructure PbSnTe lasers were developed and investigated. In this laser structure good electrical and optical confinement can be achieved by a suitable carrier concentration profile. The advantage of these lasers over PbSnTe heterostructure lasers is the perfect lattice matching between the various layers of the structure. The desired carrier concentration profile was achieved by the growth of several epitaxial layers by the LPE method on a suitable substrate. The performance of these lasers was compared with that of previous homostructure and double heterostructure lasers. (H.K.)

  19. Thermodynamic characterization of Ni3TeO6, Ni2Te3O8 and NiTe2O5

    Science.gov (United States)

    Dawar, Rimpi; Babu, R.; Ananthasivan, K.; Anthonysamy, S.

    2017-09-01

    Measurement of vapour pressure of TeO2(g) over the biphasic mixture Ni3TeO6 (s) + NiO(s) in the temperature range 1143-1272 K was carried out using transpiration-thermogravimetric technique (TTG). Gibbs energy of formation of Ni3TeO6 was obtained from the temperature dependence of vapour pressure of TeO2 (g) generated by the incongruent vapourisation reaction, Ni3TeO6 (s) → NiO(s) + TeO2 (g) + 1/2 O2 in the temperature range 1143-1272 K. An isoperibol type drop calorimeter was used to measure the enthalpy increments of Ni3TeO6, Ni2Te3O8 and NiTe2O5. Thermodynamic functions viz., heat capacity, entropy and Gibbs energy functions of these compounds were derived from the experimentally measured enthalpy increment values. Third-law analysis was carried out to ascertain absence of temperature dependent systematic errors in the measurement of vapour pressure of TeO2 (g). A value of -1265.1 ± 1.5 kJ mol-1 was obtained for Δ Hf,298K o (Ni3TeO6) using third-law analysis.

  20. Manufacturing Te/PEDOT Films for Thermoelectric Applications.

    Science.gov (United States)

    Culebras, Mario; Igual-Muñoz, Ana María; Rodríguez-Fernández, Carlos; Gómez-Gómez, María Isabel; Gómez, Clara; Cantarero, Andrés

    2017-06-21

    In this work, flexible Te films have been synthesized by electrochemical deposition using PEDOT [poly(3,4-ethylenedioxythiophene)] nanofilms as working electrodes. The Te electrodeposition time was varied to find the best thermoelectric properties of the Te/PEDOT double layers. To show the high quality of the Te films grown on PEDOT, the samples were analyzed by Raman spectroscopy, showing the three Raman active modes of Te: E 1 , A 1 , and E 2 . The X-ray diffraction spectra also confirmed the presence of crystalline Te on top of the PEDOT films. The morphology of the Te/PEDOT films was studied using scanning electron microscopy, showing a homogeneous distribution of Te along the film. Also an atomic force microscope was used to analyze the quality of the Te surface. Finally, the electrical conductivity and the Seebeck coefficient of the Te/PEDOT films were measured as a function of the Te deposition time. The films showed an excellent thermoelectric behavior, giving a maximum power factor of about 320 ± 16 μW m -1 K -2 after 2.5 h of Te electrochemical deposition, a value larger than that reported for thin films of Te. Qualitative arguments to explain this behavior are given in the discussion.

  1. Reduction in thermal conductivity of BiSbTe lump

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Kaleem [King Saud University, Sustainable Energy Technologies Center, College of Engineering, PO Box 800, Riyadh (Saudi Arabia); Wan, C. [Tsinghua University, State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Beijing (China); Al-Eshaikh, M.A.; Kadachi, A.N. [King Saud University, Research Center, College of Engineering, PO Box 800, Riyadh (Saudi Arabia)

    2017-03-15

    In this work, systematic investigations on the thermal conductivities of BiSbTe lump, microstructured pristine BiSbTe bulk and single wall carbon nanotubes (SWCNTs)/BiSbTe bulk nanocomposites were performed. BiSbTe lumps were crushed to form a coarse powder (200 μm) and effect of particle size reduction on the effective thermal conductivity of BiSbTe (200 μm) bulk were analyzed. For further reduction in the conductivity, a two pronged strategy has been employed. First, additional refinement of BiSbTe (200 μm) were performed through ball milling in an inert environment. Second, SWCNTs in 0.75, and 1.0 vol% were distributed uniformly in the fine BiSbTe ball milled powder. The results showed that the effective thermal conductivities decrease with the reduction in the particle size from lump to BiSbTe (200 μm) bulk as well as with the addition of SWCNTs accompanied by further refinement of BiSbTe particles. The significant reduction in thermal conductivities of the lump was achieved for pure BiSbTe (200 μm) bulk and 0.75 vol% of SWCNTs/BiSbTe composite. This can be ascribed to the enhanced phonon scattering by the grain boundaries between the nanostructured BiSbTe particles as well as the interfaces between BiSbTe and the low dimensional carbon nanotubes. (orig.)

  2. Phase diagram of SnTe-CdSe cross-section of SnTe+CdSe reversible SnSe+CdTe ternary reciprocal system

    International Nuclear Information System (INIS)

    Dubrovin, I.V.; Budennaya, L.D.; Mizetskaya, I.B.; Sharkina, Eh.V.

    1986-01-01

    Phase equilibrium diagram of SnTe-CdSe cross-section of Sn, Cd long Te, Se ternary reciprocal system is investigated using the methods of differential thermal, X-ray phase, and microstructural analyses. Maximum length of solid solutions on the base of SnTe corresponds to approximately 14 mol.% at 1050 K and approximately 3 mol.% of CdSe at 670 K. Region of solid solutions on the base of CdSe corresponds to less than 1 mol.% of SnTe at room temperature. SnTe-CdSe cross-section is not a quasibinar one. Equilibrium is shifted to the left in the SnTe+CdSe reversible SnSe+CdTe reciprocal system

  3. Square pulse linear transformer driver

    Directory of Open Access Journals (Sweden)

    A. A. Kim

    2012-04-01

    Full Text Available The linear transformer driver (LTD technological approach can result in relatively compact devices that can deliver fast, high current, and high-voltage pulses straight out of the LTD cavity without any complicated pulse forming and pulse compression network. Through multistage inductively insulated voltage adders, the output pulse, increased in voltage amplitude, can be applied directly to the load. The usual LTD architecture [A. A. Kim, M. G. Mazarakis, V. A. Sinebryukhov, B. M. Kovalchuk, V. A. Vizir, S. N Volkov, F. Bayol, A. N. Bastrikov, V. G. Durakov, S. V. Frolov, V. M. Alexeenko, D. H. McDaniel, W. E. Fowler, K. LeCheen, C. Olson, W. A. Stygar, K. W. Struve, J. Porter, and R. M. Gilgenbach, Phys. Rev. ST Accel. Beams 12, 050402 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050402; M. G. Mazarakis, W. E. Fowler, A. A. Kim, V. A. Sinebryukhov, S. T. Rogowski, R. A. Sharpe, D. H. McDaniel, C. L. Olson, J. L. Porter, K. W. Struve, W. A. Stygar, and J. R. Woodworth, Phys. Rev. ST Accel. Beams 12, 050401 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050401] provides sine shaped output pulses that may not be well suited for some applications like z-pinch drivers, flash radiography, high power microwaves, etc. A more suitable power pulse would have a flat or trapezoidal (rising or falling top. In this paper, we present the design and first test results of an LTD cavity that generates such a type of output pulse by including within its circular array a number of third harmonic bricks in addition to the main bricks. A voltage adder made out of a square pulse cavity linear array will produce the same shape output pulses provided that the timing of each cavity is synchronized with the propagation of the electromagnetic pulse.

  4. X-ray electron spectra of chalcogenide glasses and polycrystalline alloys of Ge-Te and As-Te systems

    International Nuclear Information System (INIS)

    Panus, V.R.

    1990-01-01

    Comparative investigation into structures of crystals and glasses in Ge-Te and As-Te two-component systems was conducted. Analysis of x-ray electron spectra of Ge-Te and As-Te systems indicates, that processes of dissociation-association resulting in formation of new structure units occur in telluride melts at synthesis temperatures. Structural chemical composition of binary glass-like alloys of Ge-Te and As-Te systems differs essentially from the one that corresponds to fusibility equilibrium curve. Oxygen doping into tellurium-base glasses results mainly in occurence of structures forecasted due to thermochemical calculation

  5. Long Silver Nanowires Synthesis by Pulsed Electrodeposition

    Directory of Open Access Journals (Sweden)

    M.R. Batevandi

    2015-09-01

    Full Text Available Silver nanowires were pulse electrodeposited into nanopore anodic alumina oxide templates. The effects of continuous and pulse electrodeposition waveform on the microstructure properties of the nanowire arrays were studied. It is seen that the microstructure of nanowire is depend to pulse condition. The off time duration of pulse waveform enables to control the growth direction of Ag nanowires.

  6. System for increasing laser pulse rate

    International Nuclear Information System (INIS)

    1980-01-01

    A technique of static elements is disclosed for combining a plurality of laser beams having time sequenced, pulsed radiation to achieve an augmented pulse rate. The technique may also be applied in a system for combining both time sequenced pulses and frequency distinct pulses for use in a system for isotope enrichment. (author)

  7. Neutron induced current pulses in fission chambers

    International Nuclear Information System (INIS)

    Taboas, A.L.; Buck, W.L.

    1978-01-01

    The mechanism of neutron induced current pulse generation in fission chambers is discussed. By application of the calculated detector transfer function to proposed detector current pulse shapes, and by comparison with actually observed detector output voltage pulses, a credible, semi-empirical, trapezoidal pulse shape of chamber current is obtained

  8. Pulse frequency in pulsed brachytherapy based on tissue repair kinetics

    International Nuclear Information System (INIS)

    Sminia, Peter; Schneider, Christoph J.; Koedooder, Kees; Tienhoven, Geertjan van; Blank, Leo E.C.M.; Gonzalez Gonzalez, Dionisio

    1998-01-01

    Purpose: Investigation of normal tissue sparing in pulsed brachytherapy (PB) relative to continuous low-dose rate irradiation (CLDR) by adjusting pulse frequency based on tissue repair characteristics. Method: Using the linear quadratic model, the relative effectiveness (RE) of a 20 Gy boost was calculated for tissue with an α/β ratio ranging from 2 to 10 Gy and a half-time of sublethal damage repair between 0.1 and 3 h. The boost dose was considered to be delivered either in a number of pulses varying from 2 to 25, or continuously at a dose rate of 0.50, 0.80, or 1.20 Gy/h. Results: The RE of 20 Gy was found to be identical for PB in 25 pulses of 0.80 Gy each h and CLDR delivered at 0.80 Gy/h for any α/β value and for a repair half-time > 0.75 h. When normal tissue repair half-times are assumed to be longer than tumor repair half-times, normal tissue sparing can be obtained, within the restriction of a fixed overall treatment time, with higher dose per pulse and longer period time (time elapsed between start of pulse n and start of pulse n + 1). An optimum relative normal tissue sparing larger than 10% was found with 4 pulses of 5 Gy every 8 h. Hence, a therapeutic gain might be obtained when changing from CLDR to PB by adjusting the physical dose in such a way that the biological dose on the tumor is maintained. The normal tissue-sparing phenomenon can be explained by an increase in RE with longer period time for tissue with high α/β ratio and fast or intermediate repair half-time, and the RE for tissue with low α/β ratio and long repair half-time remains almost constant. Conclusion: Within the benchmark of the LQ model, advantage in normal tissue-sparing is expected when matching the pulse frequency to the repair kinetics of the normal tissue exposed. A period time longer than 1 h may lead to a reduction of late normal tissue complications. This theoretical advantage emphasizes the need for better knowledge of human tissue-repair kinetics

  9. New Zealand Perspectives on Early Childhood Education: Naku Te Rourou Nau Te Rourou Ka Ora Ai Te Iwi

    Science.gov (United States)

    Tesar, Marek

    2016-01-01

    This special issue focuses on histories, pedagogies, policies, philosophies and alternative perspectives in early childhood education. "Te Whariki" is heralded as the first bicultural curriculum not only in New Zealand, but in the world. Its importance is reflected in national and international research and early childhood discourses.…

  10. River water remediation using pulsed corona, pulsed spark or ozonation

    Energy Technology Data Exchange (ETDEWEB)

    Izdebski, T.; Dors, M. [Polish Academy of Sciences, Szewalski Inst. of Fluid Flow Machiney, Fiszera (Poland). Centre for Plasma and Laser Engineering; Mizeraczyk, J. [Polish Academy of Sciences, Szewalski Inst. of Fluid Flow Machiney, Fiszera (Poland). Centre for Plasma and Laser Engineering; Gdynia Maritime Univ., Morska (Poland). Dept. of Marine Electronics

    2010-07-01

    The most common reason for epidemic formation is the pollution of surface and drinking water by wastewater bacteria. Pathogenic microorganisms that form the largest part of this are fecal bacteria, such as escherichia coli (E. coli). Wastewater treatment plants reduce the amount of the fecal bacteria by 1-3 orders of magnitude, depending on the initial number of bacteria. There is a lack of data on waste and drinking water purification by the electrohydraulic discharges method, which causes the destruction and inactivation of viruses, yeast, and bacteria. This paper investigated river water cleaning from microorganisms using pulsed corona, spark discharge and ozonization. The paper discussed the experimental setup and results. It was concluded that ozonization is the most efficient method of water disinfection as compared with pulsed spark and pulsed corona discharges. The pulsed spark discharge in water was capable of killing all microorganism similarly to ozonization, but with much lower energy efficiency. The pulsed corona discharge was found to be the less effective method of water disinfection. 21 refs., 4 figs.

  11. Strong coupling and polariton lasing in Te based microcavities embedding (Cd,Zn)Te quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Rousset, J.-G., E-mail: j-g.rousset@fuw.edu.pl; Piętka, B.; Król, M.; Mirek, R.; Lekenta, K.; Szczytko, J.; Borysiuk, J.; Suffczyński, J.; Kazimierczuk, T.; Goryca, M.; Smoleński, T.; Kossacki, P.; Nawrocki, M.; Pacuski, W. [Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, PL-02-093 Warszawa (Poland)

    2015-11-16

    We report on properties of an optical microcavity based on (Cd,Zn,Mg)Te layers and embedding (Cd,Zn)Te quantum wells. The key point of the structure design is the lattice matching of the whole structure to MgTe, which eliminates the internal strain and allows one to embed an arbitrary number of unstrained quantum wells in the microcavity. We evidence the strong light-matter coupling regime already for the structure containing a single quantum well. Embedding four unstrained quantum wells results in further enhancement of the exciton-photon coupling and the polariton lasing in the strong coupling regime.

  12. Defect characterization of CdTe thin films using a slow positron beam

    International Nuclear Information System (INIS)

    Neretina, S.; Grebennikov, D.; Mascher, P.; Hughes, R.A.; Weber, M.; Lynn, K.G.; Simpson, P.J.; Preston, J.S.

    2007-01-01

    Cadmium Telluride (CdTe) is the most well established II-VI compound largely due to its use as a photonic material. Existing applications, as well as those under consideration, are demanding increasingly stringent control of the material properties. The deposition of high quality thin films is of the utmost importance to such applications. In this regard, we present a report detailing the role of lattice mismatch in determining the film quality. Thin films were deposited on a wide variety of substrate materials using the pulsed laser deposition technique. Common to all substrates was the strong tendency towards the preferential alignment of CdTe's (111) planes parallel to the substrate's surface. X-ray diffraction analysis, however, revealed that the crystalline quality varied dramatically depending upon the substrate used with the best results yielding a single crystal film. This tendency also manifested itself in the surface morphology with higher structural perfection yielding smoother surfaces. Slow positron beam techniques revealed a strong correlation between the defect concentration and the degree of structural perfection. Simulations of the data using the POSTRAP 5 program were used to calculate the defect concentration in relative (atom -1 ) and absolute units and to determine the diffusion lengths of the positrons in the film. All of these characterization techniques point towards lattice mismatch as being the dominant mechanism in determining the quality of CdTe films. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Industrial Applications of Pulsed Power Technology

    Science.gov (United States)

    Takaki, Koichi; Katsuki, Sunao

    Recent progress of the industrial applications of pulsed power is reviewed in this paper. Repetitively operated pulsed power generators with a moderate peak power have been developed for industrial applications. These generators are reliable and low maintenance. Development of the pulsed power generators helps promote industrial applications of pulsed power for such things as food processing, medical treatment, water treatment, exhaust gas treatment, ozone generation, engine ignition, ion implantation and others. Here, industrial applications of pulsed power are classified by application for biological effects, for pulsed streamer discharges in gases, for pulsed discharges in liquid or liquid-mixture, and for bright radiation sources.

  14. Plattelandimpuls : leren door gewoon te dóen

    NARCIS (Netherlands)

    Noorduyn, L.

    2008-01-01

    Plattelandsondernemers die hun activiteiten verbreden, vergeten nogal eens serieuze aandacht te besteden aan de vermarkting van hun product. Met het project PlattelandImpuls hebben ondernemers hun vaardigheden op dat vlak kunnen verbeteren door te werken met product-marktcombinaties.

  15. ??????????? ????????? ???????????? ???????????? NH4X (?=??,?1) ??? ??????????? CdxHgi-xTe ??????? ???????? ???????????? ???????

    OpenAIRE

    ??????, ?. ?.; ?????????, ?. ?.; ???????, ?. ?.; ?????????, ?. ?.; ?????????, ?. ?.

    2004-01-01

    ?? ?????? ??????????? ?????????? ???????????? ?????? ??????? ???? ??????? CdxHgi_xTe-Hg-NH4Br ??? ??????? ?????? Hg ? ????????? ?????????? 560-860? ? ??????????? ?????? ?? = 103-=-105 ?? ????????? ????????, ??? ??????? ???????? ????? ? ??????????????? ??????, ????? ? ?????? - CdBr2, Hg, ??2. ??? ????????? ??????? ??????? ???????????? CdxHgi_xTe ??????? ? = 0.2; 0.3; 0.4 ?? ????????? ??? ??? ? ??? ?????????? ??????? ???????? ??????? (??? ?????? ?????? ????? ? ???????) ????????? ??????????? ???...

  16. TeSLA workshop betrouwbaar toetsen op afstand

    NARCIS (Netherlands)

    Brouns, Francis; Janssen, José

    2017-01-01

    Presentatie ten behoeve van workshop betrouwbaar toetsen op afstand voor docenten van de Open Universiteit Nederland betrokken in de derde TeSLA pilot. Topics: toetsfraude, toetsdesign, technologie voor authenticatie en verificatie van auteurschap, TeSLA instrumenten.

  17. TeSLA e-assessment workshop pilot 2

    OpenAIRE

    Janssen, José

    2017-01-01

    Presentatie ten behoeve van de e-assessment workshop voor docenten van de Open Universiteit Nederland betrokken in de tweede TeSLA pilot. Topics: toetsfraude, toetsdesign, technologie voor authenticatie en verificatie van auteurschap, TeSLA instrument.

  18. Perspectives of shaped pulses for EPR spectroscopy

    Science.gov (United States)

    Spindler, Philipp E.; Schöps, Philipp; Kallies, Wolfgang; Glaser, Steffen J.; Prisner, Thomas F.

    2017-07-01

    This article describes current uses of shaped pulses, generated by an arbitrary waveform generator, in the field of EPR spectroscopy. We show applications of sech/tanh and WURST pulses to dipolar spectroscopy, including new pulse schemes and procedures, and discuss the more general concept of optimum-control-based pulses for applications in EPR spectroscopy. The article also describes a procedure to correct for experimental imperfections, mostly introduced by the microwave resonator, and discusses further potential applications and limitations of such pulses.

  19. Pulsed Corona Discharge Generated By Marx Generator

    Science.gov (United States)

    Sretenovic, G. B.; Obradovic, B. M.; Kovacevic, V. V.; Kuraica, M. M.; Puric J.

    2010-07-01

    The pulsed plasma has a significant role in new environmental protection technologies. As a part of a pulsed corona system for pollution control applications, Marx type repetitive pulse generator was constructed and tested in arrangement with wire-plate corona reactor. We performed electrical measurements, and obtained voltage and current signals, and also power and energy delivered per pulse. Ozone formation by streamer plasma in air was chosen to monitor chemical activity of the pulsed corona discharge.

  20. De iep is weer te vertrouwen

    NARCIS (Netherlands)

    Hiemstra, J.A.; Beintema, N.

    2012-01-01

    De iep is door de iepziekte grotendeels uit Europa verdwenen. Mede dankzij Wagenings onderzoek zijn er nu resistente rassen op de markt. Wat nog ontbreekt is het vertrouwen van beheerders om de karakteristieke boom weer aan te planten. ‘Iepen waren synoniem met ellende.’

  1. TeV scale singlet dark matter

    International Nuclear Information System (INIS)

    Ponton, Eduardo; Randall, Lisa

    2009-01-01

    It is well known that stable weak scale particles are viable dark matter candidates since the annihilation cross section is naturally about the right magnitude to leave the correct thermal residual abundance. Many dark matter searches have focused on relatively light dark matter consistent with weak couplings to the Standard Model. However, in a strongly coupled theory, or even if the coupling is just a few times bigger than the Standard Model couplings, dark matter can have TeV-scale mass with the correct thermal relic abundance. Here we consider neutral TeV-mass scalar dark matter, its necessary interactions, and potential signals. We consider signals both with and without higher-dimension operators generated by strong coupling at the TeV scale, as might happen for example in an RS scenario. We find some potential for detection in high energy photons that depends on the dark matter distribution. Detection in positrons at lower energies, such as those PAMELA probes, would be difficult though a higher energy positron signal could in principle be detectable over background. However, a light dark matter particle with higher-dimensional interactions consistent with a TeV cutoff can in principle match PAMELA data.

  2. Effects of Ni and carbon-coated Ni addition on the thermoelectric properties of 25Bi{sub 2}Te{sub 3}+75Sb{sub 2}Te{sub 3} base composites

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Sang Min; Dharmaiah, Peyala; Femi, Olu Emmanuel; Lee, Chul Hee; Hong, Soon-Jik, E-mail: hongsj@kongju.ac.kr

    2017-07-01

    In this paper, we report the effect of nickel (Ni) and carbon coated nickel (C-Ni) on the thermoelectric and mechanical properties of 25Bi{sub 2}Te{sub 3}+75Sb{sub 2}Te{sub 3} (GA) base composites. Ni and C-Ni powders were synthesized using pulse wire evaporation and mixed with 25Bi{sub 2}Te{sub 3}+75Sb{sub 2}Te{sub 3} in a planetary ball mill. The morphology of the Ni and C-Ni powders and GA + x (x = none, Ni, or C-Ni) composites were examined using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The thermoelectric properties of the GA + x (x = none, Ni, or C-Ni) composites shows that the addition of Ni increases the carrier concentration while the presence of C-Ni reduces the carrier concentration to a level comparable to the bare sample (x = 0). Subsequently, the Seebeck coefficient of the GA + C-Ni sample increases by about 18% more than in the bare sample. The thermal conductivity of the GA + Ni and GA + C-Ni samples was considerably lower at room temperature compared to the bare sample. The mechanical properties of the GA + Ni and GA + C-Ni composite samples show a three-fold improvement compared to the bare sample. - Highlights: • Ni and carbon-coated Ni nanoparticles were incorporated into 25Bi{sub 2}Te{sub 3}+75Sb{sub 2}Te{sub 3} (BST) matrix. • Seebeck coefficient increased by 18% for BST/carbon coated Ni composites. • BST/carbon coated Ni composite reduces the thermal conductivity (21%). • The Vickers hardness of the BST/C-Ni composite samples significantly improved.

  3. High performance p-i-n CdTe and CdZnTe detectors

    CERN Document Server

    Khusainov, A K; Ilves, A G; Morozov, V F; Pustovoit, A K; Arlt, R D

    1999-01-01

    A breakthrough in the performance of p-i-n CdTe and CdZnTe detectors is reported. The detector stability has been significantly improved, allowing their use in precise gamma and XRF applications. Detectors with energy resolution close to Si and Ge were produced operating with only -30--35 deg. C cooling (by a Peltier cooler of 15x15x10 mm size and a consumed power less than 5 W). Presently detectors with volume of up to 300 mm sup 3 are available. In terms of photoelectric effect efficiency it corresponds to HPGe detectors with volumes of about 1.5 cm sup 3. The possibilities of further improvement of CdTe and CdZnTe detector characteristics are discussed in this paper.

  4. CdTe and Cd1-xZnxTe for nuclear detectors: facts and fictions

    International Nuclear Information System (INIS)

    Fougeres, P.; Siffert, P.; Hageali, M.; Koebel, J.M.; Regal, R.

    1999-01-01

    Both CdTe and Cd 1-x Zn x Te (CZT) can be considered from their physical properties as very good materials for room temperature X- and γ-rays detection. However, despite years of intense material research, no significant advance has been made to help one to choose between both semiconductors. This paper reviews a few facts about CdTe and CZT to attempt to draw a real comparison between both. THM-CdTe and HPB-CZT have been grown and characterized in Strasbourg. Crystal growth, alloying effects, transport properties and defects are reviewed on the basis of our results and the published ones. The results show that it is still very difficult to claim which one is the best

  5. Local atomic interdiffusion in CdTe/HgCdTe multilayered structures

    International Nuclear Information System (INIS)

    Kim, Y.; Ourmazd, A.; Feldman, R.D.; Rentschler, J.A.; Taylor, D.W.; Austin, R.F.

    1989-01-01

    The authors combine chemical lattice imaging with digital pattern recognition to study atomic interdiffusion at individual CdTe/HgCdTe interfaces in multi-quantum well structures. In this way they obtain quantitative composition profiles for as grown samples, and investigate their development as a function of annealing temperature. The authors' results indicate that interdiffusion depends on the position of the quantum well with respect to the surface, beginning first at quantum wells close to the surface, and proceeding towards the substrate. The authors' approach allows the quantification of interdiffusion as a function of time, temperature, and distance from the surface. The implications of these results for the stability of CdTe/HgCdTe structures, and the interpretation of X-ray data are discussed

  6. Design and construction of a mode converter from TE10(rectangular) to TE11(circular)

    International Nuclear Information System (INIS)

    Tubbing, B.J.D.

    1984-08-01

    The design and manufacturing of a wavelength mode converter from the TE 10 (rectangular) mode in oversized rectangular to the TE 11 (circular) mode in oversized circular waveguide is described. A differential equation for the cross-sectional shape of the converter was solved numerically. A stainless-steel mandrel was produced on a numerically controlled milling machine. Sixteen converters were produced by means of electroforming on one mandrel. (Auth.)

  7. From thermoelectric bulk to nanomaterials: Current progress for Bi2Te3 and CoSb3

    International Nuclear Information System (INIS)

    Peranio, N.; Eibl, O.; Baessler, S.; Nielsch, K.; Klobes, B.; Hermann, R.P.; Daniel, M.; Albrecht, M.; Goerlitz, H.; Pacheco, V.; Bedoya-Martinez, N.; Hashibon, A.; Elsaesser, C.

    2016-01-01

    Bi 2 Te 3 and CoSb 3 based nanomaterials were synthesized and their thermoelectric, structural, and vibrational properties analyzed to assess and reduce ZT-limiting mechanisms. The same preparation and/or characterization methods were applied in the different materials systems. Single-crystalline, ternary p-type Bi 15 Sb 29 Te 56 , and n-type Bi 38 Te 55 Se 7 nanowires with power factors comparable to nanostructured bulk materials were prepared by potential-pulsed electrochemical deposition in a nanostructured Al 2 O 3 matrix. p-type Sb 2 Te 3 , n-type Bi 2 Te 3 , and n-type CoSb 3 thin films were grown at room temperature using molecular beam epitaxy and were subsequently annealed at elevated temperatures. This yielded polycrystalline, single phase thin films with optimized charge carrier densities. In CoSb 3 thin films the speed of sound could be reduced by filling the cage structure with Yb and alloying with Fe yielded p-type material. Bi 2 (Te 0.91 Se 0.09 ) 3 /SiC and (Bi 0.26 Sb 0.74 ) 2 Te 3 /SiC nanocomposites with low thermal conductivities and ZT values larger than 1 were prepared by spark plasma sintering. Nanostructure, texture, chemical composition, as well as electronic and phononic excitations were investigated by X-ray diffraction, nuclear resonance scattering, inelastic neutron scattering, Moessbauer spectroscopy, and transmission electron microscopy. For Bi 2 Te 3 materials, ab-initio calculations together with equilibrium and non-equilibrium molecular dynamics simulations for point defects yielded their formation energies and their effect on lattice thermal conductivity, respectively. Current advances in thermoelectric Bi 2 Te 3 and CoSb 3 based nanomaterials are summarized. Advanced synthesis and characterization methods and theoretical modeling were combined to assess and reduce ZT-limiting mechanisms in these materials. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Effect of Te atmosphere annealing on the properties of CdZnTe single crystals

    International Nuclear Information System (INIS)

    Yu Pengfei; Jie Wanqi; Wang Tao

    2011-01-01

    Low-resistivity CdZnTe:In (CZT:In) single crystals were annealed under Te atmosphere according to the behaviors of deep-donor Te antisite. The results indicated that the star-like Cd inclusions were completely eliminated after 120 h annealing. Meanwhile, the resistivity is greatly enhanced. The resistivity of the slice annealed after 240 h was achieved as high as 1.8x10 11 Ω cm, five orders of magnitude higher than that of as-grown slice. It suggested that the deep-donor level Te antisites were successfully introduced to pin the Fermi level at the mid band-gap position. The IR transmittances of the slices were also improved, which increased as the annealing time increased. PL measurement revealed that the (D 0 ,X) peak representing high quality of CZT crystal appeared. It can be concluded that the quality of CZT crystals is obviously improved after annealing under Te atmosphere. - Highlights: → High resistivity is due to deep-donor level Te Cd . → The resistivity achieved was as high as 1.8x10 11 Ω cm. → Star-like inclusions are Cd inclusions. → (D 0 ,X) peak represents the improvement of the crystal quality.

  9. Molecular beam epitaxy of iodine-doped CdTe and (CdMg)Te

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, F.; Waag, A.; Litz, Th.; Scholl, S.; Schmitt, M.; Landwehr, G. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Bilger, G. (Zentrum fuer Sonnenenergie und Wasserstofforschung, Stuttgart (Germany))

    1994-08-01

    The n-type doping of CdTe and (CdMg)Te by the use of the solid dopant source material ZnI[sub 2] is reported. Doping levels as high as 7x10[sup 18] cm[sup -3] have been obtained in CdTe with carrier mobilities around 500 cm[sup 2]/V[center dot]s at room temperature. For a dopant incorporation higher than 1x10[sup 19] cm[sup -3] the free carrier concentration decreases, indicating the onset of a compensation mechanism, which is observed in the case of chlorine and bromine doping, too. Preliminary experiments show that with increasing Mg concentration the free carrier concentration decreases. Nevertheless, CdMgTe with a magnesium concentration x=0.37 (band gap 2.2 eV at room temperature) can be doped up to 2x10[sup 17] cm[sup -3]. The existence of deep donor levels in this CdTe based ternary is not supposed to be the only reason for the reduction of the free carrier concentration. For high Mg support during molecular beam epitaxial (MBE) growth of wide gap (CdMg)Te layers, the ZnI[sub 2] incorporation is reduced, leading to low doping levels, too

  10. New developments in clinical applications of CdTe and CdZnTe detectors

    International Nuclear Information System (INIS)

    Scheiber, C.

    1996-01-01

    This review about the medical applications of CdTe and CdZnTe is an update on the 1992 paper (1992). This new paper is legitimized by the recent progress which has been made in this field. First of all, the usefulness of a new material, i.e. CdZnTe, has been demonstrated. While the two materials are still being improved, it seems as yet too early to debate which of CdTe:Cl or CdZnTe will be the best choice. Historical applications span over the past 18 years, involving devices like miniature probes for per-operative scintigraphy or the monitoring of physiological functions and, closer to us, appliances dedicated to bone densitometry, and have been expanding as such devices have become commercially available, for many years now. Newly available microelectronic circuitry allows 2D-arrays to be built for digital quantitative X-ray (chest, dental..) and for high-resolution gamma cameras. The clinical demand is very high, especially in the field of nuclear medicine. Although there already exist clinical demonstrators, the future of such CdTe applications depends on further reduction in material and device mounting costs. New perspectives concern XCT applications, but the data resulting from research work are kept for restricted use within industrial R and D laboratories. (orig.)

  11. Excitons in tunnel coupled CdTe and (Cd,Mn)Te quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Terletskii, Oleg; Ryabchenko, Sergiy; Tereshchenko, Oleksandr [Institute of Physics NASU, pr. Nauki 46, 03680 Kyiv (Ukraine); Sugakov, Volodymyr; Vertsimakha, Ganna [Institute for Nuclear Research NASU, pr. Nauki 47, 03680 Kyiv (Ukraine); Karczewski, Grzegorz [Institute of Physics PAS, Al. Lotnikow 32/46, PL-02-668 Warsaw (Poland)

    2017-05-15

    The photoluminescence (PL) from structures containing Cd{sub 0.95}Mn{sub 0.05}Te and CdTe quantum wells (QWs) separated by a narrow (1.94 nm) barrier was studied. The PL lines of comparable intensities from several possible exciton states were observed simultaneously at energy distances substantially exceeding kT. This means that the energy transfer in the studied systems is slower than the radiative recombination of the confined excitons. For the CdTe QW width of about 8.7-9 nm, indirect excitons with the electron and heavy hole chiefly localized in the CdTe and Cd{sub 1-x}Mn{sub x}Te QWs, respectively, were detected in the magnetic field. These indirect excitons have PL energy of about 10-20 meV above the PL line of the direct excitons in the CdTe QW. The observation of the PL from the indirect excitons which are not the lowest excitations in the structure is a distinctive feature of the system. Photoluminescence intensity dependence on the energy and the magnetic field. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Pulsed neutron sources at Dubna

    International Nuclear Information System (INIS)

    Shabalin, E.P.

    1991-01-01

    In 1960 the first world repetitively pulsed reactor IBR was put into operation. It was the beginning of the story how fission based pulsed neutron sources at Dubna have survived. The engineers involved have experienced many successes and failures in the course of new sources upgrading to finally come to possess the world's brightest neutron source - IBR-2. The details are being reviewed through the paper. The fission based pulsed neutron sources did not reach their final state as yet- the conceptual views of IBR prospects are being discussed with the goal to double the thermal neutron peak flux (up to 2x10 16 ) and to enhance the cold neutron flux by 10 times (with the present one being as high that of the ISIS cold moderator). (author)

  13. Producing High Intense Attosecond Pulse Train by Interaction of Three-Color Pulse and Overdense Plasma

    Science.gov (United States)

    Salehi, M.; Mirzanejad, S.

    2017-05-01

    Amplifying the attosecond pulse by the chirp pulse amplification method is impossible. Furthermore, the intensity of attosecond pulse is low in the interaction of laser pulse and underdense plasma. This motivates us to propose using a multi-color pulse to produce the high intense attosecond pulse. In the present study, the relativistic interaction of a three-color linearly-polarized laser-pulse with highly overdense plasma is studied. We show that the combination of {{ω }}1, {{ω }}2 and {{ω }}3 frequencies decreases the instance full width at half maximum reflected attosecond pulse train from the overdense plasma surface. Moreover, we show that the three-color pulse increases the intensity of generated harmonics, which is explained by the relativistic oscillating mirror model. The obtained results demonstrate that if the three-color laser pulse interacts with overdense plasma, it will enhance two orders of magnitude of intensity of ultra short attosecond pulses in comparison with monochromatic pulse.

  14. Bomb pulse radiocarbon dating

    International Nuclear Information System (INIS)

    Tuniz, C.; Zoppi, U.; Hotchkis, M.A.C.

    2004-01-01

    Modern forensic science has to deal not only with homicides and other traditional crimes but also with more global threats such as the smuggling of nuclear materials, clandestine production of weapons of mass destruction, stockpiling of illicit drugs by state controlled groups and war crimes. Forensic applications have always benefited from the use of advanced analytical tools that can characterize materials found at crime scenes. In this paper we will discuss the use of accelerator mass spectrometry (AMS) as an ultrasensitive tool for the crime laboratories of the third millennium. An important objective in forensic science is to order past events chronologically by analysing materials associated with criminal actions. Radiocarbon dating is known to the general public for its application to historical and prehistorical investigations. Examples of forensic significance include the assassination of the Inca Atahualpa by Francisco Pizarro in the early 1530s, the possible murder of the Tyrolean Ice Man (Oetzi) 5300 years ago and the analysis of the burial cloths allegedly associated with the crucifixion of Jesus Christ . Recent murders, including those associated with war crimes in the Balkans during the 1990s, can be studied using 14 C bomb pulse dating. This method has other forensic applications, including investigation of frauds related to food and wine counterfeiting, dating of opium crops and dating of substances used in biological warfare. AMS extends the applicability of the radiocarbon method, allowing the analysis of 14 C in submilligram organic samples. Specific molecular compounds extracted from bones, hair, skin and other carbon bearing substances of forensic significance can now be dated, enhancing the sensitivity and reliability of chronological determinations. AMS can also be used to analyse rare actinide isotopes released into the environment during the clandestine production of nuclear weapons or associated with the smuggling of nuclear materials. In

  15. High power ultrashort pulse lasers

    International Nuclear Information System (INIS)

    Perry, M.D.

    1994-01-01

    Small scale terawatt and soon even petawatt (1000 terawatt) class laser systems are made possible by application of the chirped-pulse amplification technique to solid-state lasers combined with the availability of broad bandwidth materials. These lasers make possible a new class of high gradient accelerators based on the large electric fields associated with intense laser-plasma interactions or from the intense laser field directly. Here, we concentrate on the laser technology to produce these intense pulses. Application of the smallest of these systems to the production of high brightness electron sources is also introduced

  16. Microwave and pulsed power engineering

    International Nuclear Information System (INIS)

    Hofer, W.W.

    1984-01-01

    The Microwave and Pulsed Power Engineering Thrust Area is responsible for developing the short-term and long-term engineering resources required to support the growing microwave and pulsed power engineering requirements of several LLNL Programs. The responsibility of this Thrust Area is to initiate applicable research and development projects and to provide capabilities and facilities to permit engineers involved in these and other programs to make significant contributions. In this section, the principal projects are described: dielectric failure prediction using partial discharge analysis, coating dielectrics to increase surface flashover potential, and the microwave generator experiment

  17. Pulse compressor with aberration correction

    Energy Technology Data Exchange (ETDEWEB)

    Mankos, Marian [Electron Optica, Inc., Palo Alto, CA (United States)

    2015-11-30

    In this SBIR project, Electron Optica, Inc. (EOI) is developing an electron mirror-based pulse compressor attachment to new and retrofitted dynamic transmission electron microscopes (DTEMs) and ultrafast electron diffraction (UED) cameras for improving the temporal resolution of these instruments from the characteristic range of a few picoseconds to a few nanoseconds and beyond, into the sub-100 femtosecond range. The improvement will enable electron microscopes and diffraction cameras to better resolve the dynamics of reactions in the areas of solid state physics, chemistry, and biology. EOI’s pulse compressor technology utilizes the combination of electron mirror optics and a magnetic beam separator to compress the electron pulse. The design exploits the symmetry inherent in reversing the electron trajectory in the mirror in order to compress the temporally broadened beam. This system also simultaneously corrects the chromatic and spherical aberration of the objective lens for improved spatial resolution. This correction will be found valuable as the source size is reduced with laser-triggered point source emitters. With such emitters, it might be possible to significantly reduce the illuminated area and carry out ultrafast diffraction experiments from small regions of the sample, e.g. from individual grains or nanoparticles. During phase I, EOI drafted a set of candidate pulse compressor architectures and evaluated the trade-offs between temporal resolution and electron bunch size to achieve the optimum design for two particular applications with market potential: increasing the temporal and spatial resolution of UEDs, and increasing the temporal and spatial resolution of DTEMs. Specialized software packages that have been developed by MEBS, Ltd. were used to calculate the electron optical properties of the key pulse compressor components: namely, the magnetic prism, the electron mirror, and the electron lenses. In the final step, these results were folded

  18. Pulsed neutron porosity logging system

    International Nuclear Information System (INIS)

    Smith, H.D. Jr.; Smith, M.P.; Schultz, W.E.

    1978-01-01

    An improved pulsed neutron porosity logging system is provided in the present invention. A logging tool provided with a 14 MeV pulsed neutron source, an epithermal neutron detector, and a fast neutron detector is moved through a borehole. Repetitive bursts of neutrons irradiate the earth formations and, during the bursts, the fast neutron population is sampled. During the interval between bursts the epithermal neutron population is sampled along with background gamma radiation due to lingering thermal neutrons. The fast and epithermal neutron population measurements are combined to provide a measurement of formation porosity

  19. Pulse-voltage fast generator

    International Nuclear Information System (INIS)

    Valeev, R.I.; Nikiforov, M.G.; Kharchenko, A.F.

    1988-01-01

    The design is described and the test results of a four-channel pulse-voltage generator with maximum output voltage 200 kV are presented. The measurement results of generator triggering time depending on the value and polarity of the triggering voltage pulse for different triggering circuits are presented. The tests have shown stable triggering of all four channels of the generator in the range up to 40 % from selfbreakdown voltage. The generator triggering delay in the given range is <25 ns, asynchronism in channel triggering is <±1 ns

  20. Induction linacs and pulsed power

    International Nuclear Information System (INIS)

    Caporaso, G.J.

    1995-01-01

    Progress in electronic power conversion technology is making possible a new class of induction linacs that can operate at extremely high repetition rates. Advances in insulator technology, pulse forming line design and switching may also lead to a new type of high current accelerator with accelerating gradients at least an order of magnitude greater than those attainable today. The evolution of the induction accelerator pulsed power system will be discussed along with some details of these emerging technologies which are at the frontiers of accelerator technology

  1. High current pulsed positron microprobe

    International Nuclear Information System (INIS)

    Howell, R.H.; Stoeffl, W.; Kumar, A.; Sterne, P.A.; Cowan, T.E.; Hartley, J.

    1997-01-01

    We are developing a low energy, microscopically focused, pulsed positron beam for defect analysis by positron lifetime spectroscopy to provide a new defect analysis capability at the 10 10 e + s -l beam at the Lawrence Livermore National Laboratory electron linac. When completed, the pulsed positron microprobe will enable defect specific, 3-dimensional maps of defect concentrations with sub-micron resolution of defect location. By coupling these data with first principles calculations of defect specific positron lifetimes and positron implantation profiles we will both map the identity and concentration of defect distributions

  2. Pulsed neutron activation calibration technique

    International Nuclear Information System (INIS)

    Kehler, P.

    1979-01-01

    A pulsed neutron activation (PNA) for measurement of two-phase flow consists of a pulsed source of fast neutron to activate the oxygen in a steam-water mixture. Flow is measured downstream by an NaI detector. Measured counts are sorted by a multiscaler into different time channels. A counts vs. time distribution typical for two-phase flow with slip between the two phases is obtained. Proper evaluation for the counts/time distribution leads to flow-regime independent equations for the average of the inverse transil time and the average density. After calculation of the average mass flow velocity, the true mass flow is derived

  3. Anomalous Phase Change in [(GeTe)2/(Sb2Te3)]20 Superlattice Observed by Coherent Phonon Spectroscopy

    Science.gov (United States)

    Makino, K.; Saito, Y.; Mitrofanov, K.; Tominaga, J.; Kolobov, A. V.; Nakano, T.; Fons, P.; Hase, M.

    The temperature-dependent ultrafast coherent phonon dynamics of topological (GeTe)2/(Sb2Te3) super lattice phase change memory material was investigated. By comparing with Ge-Sb-Te alloy, a clear contrast suggesting the unique phase change behavior was found.

  4. Apparatus for generating nonlinear pulse patterns

    Science.gov (United States)

    Nakamura, N.M.I.

    Apparatus for generating a plurality of nonlinear pulse patterns from a single linear pulse pattern. A first counter counts the pulses of the linear pulse pattern and a second counter counts the pulses of the nonlinear pulse pattern. A comparator compares the counts of both counters, and in response to an equal count, a gate is enabled to gate a pulse of the linear pattern as a pulse of the nonlinear pattern, the latter also resetting the first counter. Presettable dividers divide the pulses of each pattern before they are counted by the respective counters. Apparatus for generating a logarithmic pulse pattern from a linear pulse pattern to any log base is described. In one embodiment, a shift register is used in place of the second counter to be clocked by each pulse of the logarithmic pattern to generate the pattern. In another embodiment, a memory stores the logarithmic pattern and is addressed by the second counter which is clocked by the pulses of the logarithmic pulse pattern.

  5. Updating the induction module from single-pulse to double-pulses

    International Nuclear Information System (INIS)

    Huang Ziping; Wang Huacen; Deng Jianjun

    2002-01-01

    A double-pulse Linear Induced Accelerator (LIA) module is reconstructed based on a usual simple-pulse LIA module. By changing the length of one of the cables between the inductive cell and the Blumlein pulse forming line, two induction pulses with 90 ns FWHM and 150 kV pulse voltage are generated by the ferrite cores inductive cell. The interval time of the pulses is adjustable by changing the lengths of the cable

  6. Dynamic Characterization of Fiber Optical Chirped Pulse Amplification for Sub-ps Pulses

    DEFF Research Database (Denmark)

    Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Rishøj, Lars Søgaard

    2013-01-01

    We investigate experimentally the propagation of sub-picosecond pulses in fiber optical parametric chirped pulse amplifiers, showing a significant broadening of the pulses from 450 fs up to 720 fs due to dispersion and self-phase modulation.......We investigate experimentally the propagation of sub-picosecond pulses in fiber optical parametric chirped pulse amplifiers, showing a significant broadening of the pulses from 450 fs up to 720 fs due to dispersion and self-phase modulation....

  7. Pulse-height loss in the signal readout circuit of compound semiconductor detectors

    Science.gov (United States)

    Nakhostin, M.; Hitomi, K.

    2018-06-01

    Compound semiconductor detectors such as CdTe, CdZnTe, HgI2 and TlBr are known to exhibit large variations in their charge collection times. This paper considers the effect of such variations on the measurement of induced charge pulses by using resistive feedback charge-sensitive preamplifiers. It is shown that, due to the finite decay-time constant of the preamplifiers, the capacitive decay during the signal readout leads to a variable deficit in the measurement of ballistic signals and a digital pulse processing method is employed to correct for it. The method is experimentally examined by using sampled pulses from a TlBr detector coupled to a charge-sensitive preamplifier with 150 μs of decay-time constant and 20 % improvement in the energy resolution of the detector at 662 keV is achieved. The implications of the capacitive decay on the correction of charge-trapping effect by using depth-sensing technique are also considered.

  8. Discrimination of alpha particles in CdZnTe detectors with coplanar grid for the COBRA experiment

    Energy Technology Data Exchange (ETDEWEB)

    Rebber, Henning [Universitaet Hamburg, Institut fuer Experimentalphysik, Luruper Chaussee 149, 22761 Hamburg (Germany); Collaboration: COBRA-Collaboration

    2016-07-01

    The aim of the COBRA experiment is the search for neutrinoless double beta decay using CdZnTe semiconductor detectors. A background rate in the order of 10{sup -3} counts per keV, kg and year is intended in order to be sensitive to a half-life larger than 10{sup 26} years. Measurements from a demonstrator setup and Monte Carlo simulations indicate that a large background component is due to alpha particles. These generate charge clouds of only few μm in diameter in the detector, leading to characteristic pulse features. Parameter-based cut criteria were developed to discriminate alpha events by means of their pulse shapes. The cuts were tested on data from alpha and beta irradiation of a (1 x 1 x 1) cm{sup 3} CdZnTe detector with coplanar grid. The pulse shapes of all event signals were read out by FADCs with a sampling rate of 100 MHz. The signals were reproduced by a detector simulation which hence was used to study the cuts for energies up to 3 MeV and different detector regions.

  9. Characterization of Cr-doped Sb{sub 2}Te{sub 3} films and their application to phase-change memory

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qing; Xia, Yangyang; Zheng, Yonghui [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050 (China); University of the Chinese Academy of Sciences, Beijing, 100049 (China); Shanghai Key Laboratory of Nanofabrication Technology for Memory, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050 (China); Liu, Bo; Zhu, Min; Song, Sannian; Lv, Shilong; Cheng, Yan; Song, Zhitang; Feng, Songlin [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050 (China); Shanghai Key Laboratory of Nanofabrication Technology for Memory, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050 (China); Huo, Ruru [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050 (China); Shanghai Key Laboratory of Nanofabrication Technology for Memory, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050 (China); Shanghaitech University, Shanghai, 200031 (China)

    2015-08-15

    Phase-change memory (PCM) is regarded as one of the most promising candidates for the next-generation nonvolatile memory. Its storage medium, phase-change material, has attracted continuous exploration. Along the traditional GeTe-Sb{sub 2}Te{sub 3} tie line, the binary compound Sb{sub 2}Te{sub 3} is a high-speed phase-change material matrix. However, the low crystallization temperature prevents its practical application in PCM. Here, Cr is doped into Sb{sub 2}Te{sub 3}, called Cr-Sb{sub 2}Te{sub 3} (CST), to improve the thermal stability. We find that, with increase of the Cr concentration, grains are obviously refined. However, all the CST films exhibit a single hexagonal phase as Sb{sub 2}Te{sub 3} without phase separation. Also, the Cr helps to inhibit oxidation of Sb atoms. For the selected film CST{sub 1}0.5, the resistance ratio between amorphous and crystalline states is more than two orders of magnitude; the temperature for 10-year data retention is 120.8 C, which indicates better thermal stability than GST and pure Sb{sub 2}Te{sub 3}. PCM cells based on CST{sub 1}0.5 present small threshold current/voltage (4 μA/0.67 V). In addition, the cell can be operated by a low SET/RESET voltage pulse (1.1 V/2.4 V) with 50 ns width. Thus, Cr-Sb{sub 2}Te{sub 3} with suitable composition is a promising novel phase-change material used for PCM with high speed and good thermal stability performances. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Density of liquid Hg(1-x)Cd(x)Te

    Science.gov (United States)

    Chandra, D.; Holland, L. R.

    1983-01-01

    Negative thermal expansion has been established in liquid Hg(1-x)Cd(x)Te for x less than 0.2 employing a pycnometric method. Pure HgTe increases in density from its melting point at 670 C to a maximum value at 750 C, where normal thermal expansion progressively resumes. The dependence of density on temperature for liquid Hg(1-x)Cd(x)Te arises almost exclusively from the HgTe portion of the melt, while CdTe acts as a diluent. The temperature corresponding to the maximum density changes slightly with composition, increasing by about 5 C for x = 0.1.

  11. First observation of multi-pulse X-ray train via multi-collision laser Compton scattering

    International Nuclear Information System (INIS)

    Kuroda, R.; Toyokawa, H.; Yasumoto, M.; Ikeura-Sekiguchi, H.; Koike, M.; Yamada, K.; Yanagida, T.; Nakajyo, T.; Sakai, F.

    2009-01-01

    A compact hard X-ray source via laser Compton scattering (LCS) has been developed for biological and medical applications at the National Institute of Advanced Industrial Science and Technology (AIST) in Japan. The multi-collision LCS has been investigated in order to enhance the X-ray yields. The first observation of multi-pulse X-ray train with 6 pulses via the multi-collision LCS has been successfully demonstrated between the multi-bunch electron train with 6 bunches and the multi-pulse Ti:Sa laser train with 6 pulses. The 32 MeV electron train was generated from a Cs 2 Te photocathode rf gun with a multi-pulse UV laser and the S-band linac. The Ti:Sa laser train was obtained with the chirp pulse amplification (CPA) including the modified regenerative amplifier. The X-ray train with 6 pulses with 12.6 ns spacing was observed with the micro-channel plate (MCP). The maximum energy of the X-ray is analytically estimated to be about 24 keV and the total number of generated photons was calculated to be about 1.8x10 6 photons/train.

  12. Calculation of femtosecond pulse laser induced damage threshold for broadband antireflective microstructure arrays.

    Science.gov (United States)

    Jing, Xufeng; Shao, Jianda; Zhang, Junchao; Jin, Yunxia; He, Hongbo; Fan, Zhengxiu

    2009-12-21

    In order to more exactly predict femtosecond pulse laser induced damage threshold, an accurate theoretical model taking into account photoionization, avalanche ionization and decay of electrons is proposed by comparing respectively several combined ionization models with the published experimental measurements. In addition, the transmittance property and the near-field distribution of the 'moth eye' broadband antireflective microstructure directly patterned into the substrate material as a function of the surface structure period and groove depth are performed by a rigorous Fourier model method. It is found that the near-field distribution is strongly dependent on the periodicity of surface structure for TE polarization, but for TM wave it is insensitive to the period. What's more, the femtosecond pulse laser damage threshold of the surface microstructure on the pulse duration taking into account the local maximum electric field enhancement was calculated using the proposed relatively accurate theoretical ionization model. For the longer incident wavelength of 1064 nm, the weak linear damage threshold on the pulse duration is shown, but there is a surprising oscillation peak of breakdown threshold as a function of the pulse duration for the shorter incident wavelength of 532 nm.

  13. High-power rf pulse compression with SLED-II at SLAC

    International Nuclear Information System (INIS)

    Nantista, C.

    1993-04-01

    Increasing the peak rf power available from X-band microwave tubes by means of rf pulse compression is envisioned as a way of achieving the few-hundred-megawatt power levels needed to drive a next-generation linear collider with 50--100 MW klystrons. SLED-II is a method of pulse compression similar in principal to the SLED method currently in use on the SLC and the LEP injector linac. It utilizes low-los resonant delay lines in place of the storage cavities of the latter. This produces the added benefit of a flat-topped output pulse. At SLAC, we have designed and constructed a prototype SLED-II pulse-compression system which operates in the circular TE 01 mode. It includes a circular-guide 3-dB coupler and other novel components. Low-power and initial high-power tests have been made, yielding a peak power multiplication of 4.8 at an efficiency of 40%. The system will be used in providing power for structure tests in the ASTA (Accelerator Structures Test Area) bunker. An upgraded second prototype will have improved efficiency and will serve as a model for the pulse compression system of the NLCTA (Next Linear Collider Test Accelerator)

  14. Preparation and observation of an artifact-free Ge2Sb2Te5 TEM specimen by the small angle cleavage technique

    International Nuclear Information System (INIS)

    Kim, M.S.; Kim, H.G.

    2006-01-01

    The amorphous Ge 2 Sb 2 Te 5 thin film for the application to the non-volatile memory device was prepared by the pulsed laser deposition on a SiO2/Si substrate. The amorphous Ge 2 Sb 2 Te 5 which has the T C around 150 deg. C is readily crystallized when exposed to a comparable heat such as the Ar beam irradiation during the conventional ion milling process. Retaining its amorphous initial phase is important in order to precisely observe and understand the crystallization behaviour whether it be the sample for a pure materialistic research or applied into the device. To avoid such deterioration of the film's amorphous nature, the complete mechanical TEM specimen preparation which is called the small angle cleavage technique (SACT) was adopted to show thermally undisturbed, an artifact-free amorphous Ge 2 Sb 2 Te 5 TEM specimen. The two distinctive amorphous and crystalline phases has been observed by the HRTEM study

  15. RIIM two-pulse injector experiments

    International Nuclear Information System (INIS)

    Mazarakis, M.G.; Smith, D.L.; Jones, E.E.; Hasti, D.E.; Jojola, J.M.; Lehmann, M.

    1987-01-01

    The RADLAC-II foilless diode injector was operated under double pulse conditions utilizing the RIIM accelerator as the test bed. The original RIIM accelerator pulse-power network was modified to provide for the generation, transmission, and delivery to the foilless diode of two distinct voltage pulses with variable interpulse separation from 0 to 2 ms. Two pulse-power assemblies were investigated and will be presented in connection with the diode performance. In both cases, the generated plasma and an excessive neutral gas release, following the first pulse, prevented the diode from producing a second beam pulse for interpulse separations larger than ∼1 μs. 4 refs

  16. Arbitrarily accurate twin composite π -pulse sequences

    Science.gov (United States)

    Torosov, Boyan T.; Vitanov, Nikolay V.

    2018-04-01

    We present three classes of symmetric broadband composite pulse sequences. The composite phases are given by analytic formulas (rational fractions of π ) valid for any number of constituent pulses. The transition probability is expressed by simple analytic formulas and the order of pulse area error compensation grows linearly with the number of pulses. Therefore, any desired compensation order can be produced by an appropriate composite sequence; in this sense, they are arbitrarily accurate. These composite pulses perform equally well as or better than previously published ones. Moreover, the current sequences are more flexible as they allow total pulse areas of arbitrary integer multiples of π .

  17. Femtosecond pulse shaping using the geometric phase.

    Science.gov (United States)

    Gökce, Bilal; Li, Yanming; Escuti, Michael J; Gundogdu, Kenan

    2014-03-15

    We demonstrate a femtosecond pulse shaper that utilizes polarization gratings to manipulate the geometric phase of an optical pulse. This unique approach enables circular polarization-dependent shaping of femtosecond pulses. As a result, it is possible to create coherent pulse pairs with orthogonal polarizations in a 4f pulse shaper setup, something until now that, to our knowledge, was only achieved via much more complex configurations. This approach could be used to greatly simplify and enhance the functionality of multidimensional spectroscopy and coherent control experiments, in which multiple coherent pulses are used to manipulate quantum states in materials of interest.

  18. Zn2(TeO3Br2

    Directory of Open Access Journals (Sweden)

    Mats Johnsson

    2008-05-01

    Full Text Available Single crystals of dizinc tellurium dibromide trioxide, Zn2(TeO3Br2, were synthesized via a transport reaction in sealed evacuated silica tubes. The compound has a layered crystal structure in which the building units are [ZnO4Br] distorted square pyramids, [ZnO2Br2] distorted tetrahedra, and [TeO3E] tetrahedra (E being the 5s2 lone pair of Te4+ joined through sharing of edges and corners to form layers of no net charge. Bromine atoms and tellurium lone pairs protrude from the surfaces of each layer towards adjacent layers. This new compound Zn2(TeO3Br2 is isostructural with the synthetic compounds Zn2(TeO3Cl2, CuZn(TeO32, Co2(TeO3Br2 and the mineral sophiite, Zn2(SeO3Cl2.

  19. PUSPATI Triga Reactor pulsing parameters

    Energy Technology Data Exchange (ETDEWEB)

    Auu, Gui Ah; Abu, Puad Haji; Yunus, Yaziz [PUSPATI, Selangor (Malaysia)

    1984-06-01

    The pulsing experiment was carried out as part of the commissioning activites of PUSPATI TRIGA Reactor (PTR). Several parameters of PTR were deduced from the experiment. It was found that the maximum temperature of the fuel was far below the safety limit when the maximum allowable positive reactivity of $3.00 was inserted into the core. The peak power achieved was 1354 Mw.

  20. High energy HF pulsed lasers

    International Nuclear Information System (INIS)

    Patterson, E.L.; Gerber, R.A.

    1976-01-01

    Recent experiments show that pulsed HF lasers are capable of producing high energy with good efficiency. Preliminary experiments show that the laser radiation from the high-gain medium can be controlled with a low-power probe laser beam or with low-level feedback. These results indicate that the HF laser may have potential for second-generation laser fusion experiments

  1. Pulsed neutron generator for logging

    International Nuclear Information System (INIS)

    Thibideau, F.D.

    1977-01-01

    A pulsed neutron generator for uranium logging is described. This generator is one component of a prototype uranium logging probe which is being developed by SLA to detect, and assay, uranium by borehole logging. The logging method is based on the measurement of epithermal neutrons resulting from the prompt fissioning of uranium from a pulsed source of 17.6 MeV neutrons. An objective of the prototype probe was that its diameter not exceed 2.75 inches, which would allow its use in conventional rotary drill holes of 4.75-inch diameter. This restriction limited the generator to a maximum 2.375-inch diameter. The performance requirements for the neutron generator specified that it operate with a nominal output of 5 x 10 6 neutrons/pulse at up to 100 pulses/second for a one-hour period. The development of a neutron generator meeting the preliminary design goals was completed and two prototype models were delivered to SLA. These two generators have been used by SLA to log a number of boreholes in field evaluation of the probe. The results of the field evaluations have led to the recommendation of several changes to improve the probe's operation. Some of these changes will require additional development effort on the neutron generator. It is expected that this work will be performed during 1977. The design and operation of the first prototype neutron generators is described

  2. Pulse oximetry for perioperative monitoring

    DEFF Research Database (Denmark)

    Pedersen, Tom; Nicholson, Amanda; Hovhannisyan, Karen

    2014-01-01

    or infectious complications were detected in the two groups. The duration of hospital stay was a median of five days in both groups, and equal numbers of in-hospital deaths were reported in the two groups. Continuous pulse oximetry has the potential to increase vigilance and decrease pulmonary complications...

  3. A computerized pulse radiolysis system

    International Nuclear Information System (INIS)

    Eriksen, T.E.; Lind, J.; Reitberger, T.

    1976-01-01

    A computer based pulse radiolysis system for gathering and handling of transient optical absorption and electric conductivity data is presented. The system has been developed around a Biomation 8100 transient recorder and a PDP 11/40 (Digital Equipment Corp) computer. (author)

  4. Airbreathing Pulse Detonation Engine Performance

    Science.gov (United States)

    Povinelli, Louis A.; Yungster, Shaye

    2002-01-01

    This paper presents performance results for pulse detonation engines (PDE) taking into account the effects of dissociation and recombination. The amount of sensible heat recovered through recombination in the PDE chamber and exhaust process was found to be significant. These results have an impact on the specific thrust, impulse and fuel consumption of the PDE.

  5. Thermodynamical aspects of pulse tubes

    NARCIS (Netherlands)

    Waele, de A.T.A.M.; Steijaert, P.P.; Gijzen, J.

    1997-01-01

    The cooling power of cryocoolers is determined by the work done by the compressor and the entropy produced by the irreversible processes in the various components of the system. In this paper we discuss the thermodynamics of pulse tubes, but many of the relationships are equally valid for other

  6. Instrumentation at pulsed neutron sources

    International Nuclear Information System (INIS)

    Carpenter, J.M.; Lander, G.H.; Windsor, C.G.

    1984-01-01

    Scientific investigations involving the use of neutron beams have been centered at reactor sources for the last 35 years. Recently, there has been considerable interest in using the neutrons produced by accelerator driven (pulsed) sources. Such installations are in operation in England, Japan, and the United States. In this article a brief survey is given of how the neutron beams are produced and how they can be optimized for neutron scattering experiments. A detailed description is then given of the various types of instruments that have been, or are planned, at pulsed sources. Numerous examples of the scientific results that are emerging are given. An attempt is made throughout the article to compare the scientific opportunities at pulsed sources with the proven performance of reactor installations, and some familiarity with the latter and the general field of neutron scattering is assumed. New areas are being opened up by pulsed sources, particularly with the intense epithermal neutron beams, which promise to be several orders of magnitude more intense than can be obtained from a thermal reactor

  7. A novel time-to-pulse height converter for fast-neutron time-of-flight techniques

    International Nuclear Information System (INIS)

    Christiansen, J.

    1962-01-01

    An electronic time-to-pulse height converter is described which uses a multiplicative method instead of the usual one of adding overlapping pulses. This is achieved by a coincidence of a linear sawtooth and a sharply clipped needle-pulse. The sawtooth is fed to the grid of a beam-deflecting tube (E80T) and the needle-pulse is applied to the deflecting plates and opens the tube only during a time-interval of about 5.10 -9 s. The plate gets a charge proportional to the time-difference between the start of the sawtooth and the needle pulse. The plate-pulse is stretched and amplified and its height represents a measurement of the time-difference. With this method we got a time resolution of 2τ = 7 x 10 -12 s with artificial pulses, 2τ = 3 x 10 -10 s with Co 60 γ-coincidences by using NE 102 plastic crystals and 2τ = 1.4 x 10 -9 s with 511-keV γ-coincidences using NaI(Te) crystals. The method was also used with pulsed beam techniques. In this case we got from the pulsing RF an 8-Mc, sharply-peaked pulse-sequence, which was fed to the E80T plates. We had a time-resolution of 2τ = 1.1 x 10 -9 s with 4-MeV neutrons using plastic crystals 0.7 in long. Normally the region of linear response was 30 ns but it was possible to go up to 120 ns. (author) [fr

  8. Subgap time of flight: A spectroscopic study of deep levels in semi-insulating CdTe:Cl

    Energy Technology Data Exchange (ETDEWEB)

    Pousset, J.; Farella, I.; Cola, A., E-mail: adriano.cola@le.imm.cnr.it [Institute for Microelectronics and Microsystems—Unit of Lecce, National Council of Research (IMM/CNR), Lecce I-73100 (Italy); Gambino, S. [Dipartimento di Matematica e Fisica “Ennio De Giorgi,” Università del Salento, Lecce I-73100 (Italy); CNR NANOTEC—Istituto di Nanotecnologia, Polo di Nanotecnologia c/o Campus Ecotekne, via Monteroni, 73100 Lecce (Italy)

    2016-03-14

    We report on a study of deep levels in semi-insulating CdTe:Cl by means of a time-of-flight spectral approach. By varying the wavelength of a pulsed optical source within the CdTe energy gap, transitions to/from localized levels generate free carriers which are analysed through the induced photocurrent transients. Both acceptor-like centers, related to the A-center, and a midgap level, 0.725 eV from the valence band, have been detected. The midgap level is close to the Fermi level and is possibly a recombination center responsible for the compensation mechanism. When the irradiance is varied, either linear or quadratic dependence of the electron and hole collected charge are observed, depending on the dominant optical transitions. The analysis discloses the potentiality of such a novel approach exploitable in the field of photorefractive materials as well as for deep levels spectroscopy.

  9. Subgap time of flight: A spectroscopic study of deep levels in semi-insulating CdTe:Cl

    International Nuclear Information System (INIS)

    Pousset, J.; Farella, I.; Cola, A.; Gambino, S.

    2016-01-01

    We report on a study of deep levels in semi-insulating CdTe:Cl by means of a time-of-flight spectral approach. By varying the wavelength of a pulsed optical source within the CdTe energy gap, transitions to/from localized levels generate free carriers which are analysed through the induced photocurrent transients. Both acceptor-like centers, related to the A-center, and a midgap level, 0.725 eV from the valence band, have been detected. The midgap level is close to the Fermi level and is possibly a recombination center responsible for the compensation mechanism. When the irradiance is varied, either linear or quadratic dependence of the electron and hole collected charge are observed, depending on the dominant optical transitions. The analysis discloses the potentiality of such a novel approach exploitable in the field of photorefractive materials as well as for deep levels spectroscopy.

  10. Electrical properties of NiAs-type MnTe films with preferred crystallographic plane of (110)

    Energy Technology Data Exchange (ETDEWEB)

    Yang, L.; Wang, Z. H., E-mail: zhwang@imr.ac.cn; Zhang, Z. D. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2016-01-28

    NiAs-type manganese telluride (MnTe) films with preferred crystallographic plane of (110) were prepared on Si/SiO{sub 2} substrates by pulsed laser deposition. X-ray diffraction (XRD) of the films was studied at different temperatures. The XRD peak of MnTe (110) films shifts to higher angle with decreasing temperature, showing the decrease of the lattice parameter. Resistivity of the films was studied in the temperature range of 2–350 K. The bump between 150 and 250 K was observed in the films, which may be related to the special s-d and p-d overlaps induced by the compressed lattice. The magnon drag effect near its Néel temperature T{sub N} and enlarged magnetic-elastic coupling below 100 K were observed and analyzed in details.

  11. Properties of Hg1-xCdxTe epitaxial films grown on (211)CdTe and (211)CdZnTe

    International Nuclear Information System (INIS)

    Di Stefano, M.C.; Gilabert, U.; Heredia, E.; Trigubo, A.B.

    2004-01-01

    Hg 1-x Cd x Te (MCT) epitaxial films have been grown employing single crystalline substrates of CdTe and Cd 0.96 Zn 0.04 Te with (211)Cd and (211)Te crystalline orientations. The Isothermal Vapor Phase Epitaxy (ISOVPE) technique without Hg overpressure has been used for the epitaxial growth. Substrates and films were characterized by optical microscopy, chemical etching and X ray diffraction (Laue technique). The electrical properties were determined by Hall effect measurements. The characterization results allowed to evaluate the crystalline quality of MCT films. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. HgCdTe APD-based linear-mode photon counting components and ladar receivers

    Science.gov (United States)

    Jack, Michael; Wehner, Justin; Edwards, John; Chapman, George; Hall, Donald N. B.; Jacobson, Shane M.

    2011-05-01

    Linear mode photon counting (LMPC) provides significant advantages in comparison with Geiger Mode (GM) Photon Counting including absence of after-pulsing, nanosecond pulse to pulse temporal resolution and robust operation in the present of high density obscurants or variable reflectivity objects. For this reason Raytheon has developed and previously reported on unique linear mode photon counting components and modules based on combining advanced APDs and advanced high gain circuits. By using HgCdTe APDs we enable Poisson number preserving photon counting. A metric of photon counting technology is dark count rate and detection probability. In this paper we report on a performance breakthrough resulting from improvement in design, process and readout operation enabling >10x reduction in dark counts rate to ~10,000 cps and >104x reduction in surface dark current enabling long 10 ms integration times. Our analysis of key dark current contributors suggest that substantial further reduction in DCR to ~ 1/sec or less can be achieved by optimizing wavelength, operating voltage and temperature.

  13. Nanosecond bipolar pulse generators for bioelectrics.

    Science.gov (United States)

    Xiao, Shu; Zhou, Chunrong; Yang, Enbo; Rajulapati, Sambasiva R

    2018-04-26

    Biological effects caused by a nanosecond pulse, such as cell membrane permeabilization, peripheral nerve excitation and cell blebbing, can be reduced or cancelled by applying another pulse of reversed polarity. Depending on the degree of cancellation, the pulse interval of these two pulses can be as long as dozens of microseconds. The cancellation effect diminishes as the pulse duration increases. To study the cancellation effect and potentially utilize it in electrotherapy, nanosecond bipolar pulse generators must be made available. An overview of the generators is given in this paper. A pulse forming line (PFL) that is matched at one end and shorted at the other end allows a bipolar pulse to be produced, but no delay can be inserted between the phases. Another generator employs a combination of a resistor, an inductor and a capacitor to form an RLC resonant circuit so that a bipolar pulse with a decaying magnitude can be generated. A third generator is a converter, which converts an existing unipolar pulse to a bipolar pulse. This is done by inserting an inductor in a transmission line. The first phase of the bipolar pulse is provided by the unipolar pulse's rising phase. The second phase is formed during the fall time of the unipolar pulse, when the inductor, which was previously charged during the flat part of the unipolar pulse, discharges its current to the load. The fourth type of generator uses multiple MOSFET switches stacked to turn on a pre-charged, bipolar RC network. This approach is the most flexible in that it can generate multiphasic pulses that have different amplitudes, delays, and durations. However, it may not be suitable for producing short nanosecond pulses (<100 ns), whereas the PFL approach and the RLC approach with gas switches are used for this range. Thus, each generator has its own advantages and applicable range. Copyright © 2018 Elsevier B.V. All rights reserved.

  14. TeV gravity in four dimensions?

    International Nuclear Information System (INIS)

    Calmet, Xavier; Hsu, Stephen D.H.

    2008-01-01

    We describe a model in which the fundamental scale M * of the theory which unifies gravity and quantum mechanics is in the TeV range, but without requiring additional spacetime dimensions. The weakness of gravity at low energies is due to a large vacuum expectation of a dilaton like field. The model requires a small dimensionless parameter (the self-coupling of the dilaton) but no fine-tuning. We discuss in detail the dynamical assumptions about non-perturbative quantum gravity required within the model. We observe that M * could be quite small, less than a TeV, and that the model could lead to copious strong coupling effects at the LHC. However, semiclassical black holes will not be produced

  15. Wave equations for pulse propagation

    International Nuclear Information System (INIS)

    Shore, B.W.

    1987-01-01

    Theoretical discussions of the propagation of pulses of laser radiation through atomic or molecular vapor rely on a number of traditional approximations for idealizing the radiation and the molecules, and for quantifying their mutual interaction by various equations of propagation (for the radiation) and excitation (for the molecules). In treating short-pulse phenomena it is essential to consider coherent excitation phenomena of the sort that is manifest in Rabi oscillations of atomic or molecular populations. Such processes are not adequately treated by rate equations for excitation nor by rate equations for radiation. As part of a more comprehensive treatment of the coupled equations that describe propagation of short pulses, this memo presents background discussion of the equations that describe the field. This memo discusses the origin, in Maxwell's equations, of the wave equation used in the description of pulse propagation. It notes the separation into lamellar and solenoidal (or longitudinal and transverse) and positive and negative frequency parts. It mentions the possibility of separating the polarization field into linear and nonlinear parts, in order to define a susceptibility or index of refraction and, from these, a phase and group velocity. The memo discusses various ways of characterizing the polarization characteristics of plane waves, that is, of parameterizing a transverse unit vector, such as the Jones vector, the Stokes vector, and the Poincare sphere. It discusses the connection between macroscopically defined quantities, such as the intensity or, more generally, the Stokes parameters, and microscopic field amplitudes. The material presented here is a portion of a more extensive treatment of propagation to be presented separately. The equations presented here have been described in various books and articles. They are collected here as a summary and review of theory needed when treating pulse propagation

  16. Cryosurgery with pulsed electric fields.

    Directory of Open Access Journals (Sweden)

    Charlotte S Daniels

    Full Text Available This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused

  17. Cryosurgery with Pulsed Electric Fields

    Science.gov (United States)

    Daniels, Charlotte S.; Rubinsky, Boris

    2011-01-01

    This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF) are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF) was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused PEFs could be used to

  18. Compact rf polarizer and its application to pulse compression systems

    Directory of Open Access Journals (Sweden)

    Matthew Franzi

    2016-06-01

    Full Text Available We present a novel method of reducing the footprint and increasing the efficiency of the modern multi-MW rf pulse compressor. This system utilizes a high power rf polarizer to couple two circular waveguide modes in quadrature to a single resonant cavity in order to replicate the response of a traditional two cavity configuration using a 4-port hybrid. The 11.424 GHz, high-Q, spherical cavity has a 5.875 cm radius and is fed by the circularly polarized signal to simultaneously excite the degenerate TE_{114} modes. The overcoupled spherical cavity has a Q_{0} of 9.4×10^{4} and coupling factor (β of 7.69 thus providing a loaded quality factor Q_{L} of 1.06×10^{4} with a fill time of 150 ns. Cold tests of the polarizer demonstrated good agreement with the numerical design, showing transmission of -0.05  dB and reflection back to the input rectangular WR 90 waveguide less than -40  dB over a 100 MHz bandwidth. This novel rf pulse compressor was tested at SLAC using XL-4 Klystron that provided rf power up to 32 MW and generated peak output power of 205 MW and an average of 135 MW over the discharged signal. A general network analysis of the polarizer is discussed as well as the design and high power test of the rf pulse compressor.

  19. Optically detected SdH oscillations in CdTe/(CdMg)Te and CdTe/(CdMnMg)Te modulation doped quantum wells

    International Nuclear Information System (INIS)

    Shen, J.X.; Ossau, W.; Fischer, F.; Waag, A.; Landwehr, G.

    1995-01-01

    Oscillations of photoluminescence properties in external magnetic fields are investigated in CdTe modulation doped quantum wells. The oscillatory behaviour of the luminescence intensity, the line width and the g factor is due to many-body effects in the 2-dimensional electron gas. The oscillation of photoluminescence intensity can be easily used as optically detected Shubnikov de Haas effect to determine the electron concentration in quantum wells without contacts. (author)

  20. Optically detected SdH oscillations in CdTe/(CdMg)Te and CdTe/(CdMnMg)Te modulation doped quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Shen, J.X.; Ossau, W.; Fischer, F.; Waag, A.; Landwehr, G. [Physikalisches Institut der Uniwersitaet Wuerzburg, Wuerzburg (Germany)

    1995-12-31

    Oscillations of photoluminescence properties in external magnetic fields are investigated in CdTe modulation doped quantum wells. The oscillatory behaviour of the luminescence intensity, the line width and the g factor is due to many-body effects in the 2-dimensional electron gas. The oscillation of photoluminescence intensity can be easily used as optically detected Shubnikov de Haas effect to determine the electron concentration in quantum wells without contacts. (author). 5 refs, 3 figs, 1 tab.

  1. Multi-TeV muon colliders

    International Nuclear Information System (INIS)

    Neuffer, D.

    1986-01-01

    The possibility that muons may be used in a future generation of high-energy high-luminosity μ + μ - and μ - p colliders is presented. The problem of collecting and cooling high-intensity muon bunches is discussed and ionization cooling is described. High-energy collider scenarios are outlined; muon colliders may become superior to electron colliders in the multi-TeV energy range

  2. Controlled generation of a single Trichel pulse and a series of single Trichel pulses in air

    Science.gov (United States)

    Mizeraczyk, Jerzy; Berendt, Artur; Akishev, Yuri

    2018-04-01

    In this paper, a simple method for the controlled generation of a single Trichel pulse or a series of single Trichel pulses of a regulated repetition frequency in air is proposed. The concept of triggering a single Trichel pulse or a series of such pulses is based on the precise controlling the voltage inception of the negative corona, which can be accomplished through the use of a ramp voltage pulse or a series of such pulses with properly chosen ramp voltage pulse parameters (rise and fall times, and ramp voltage pulse repetition frequency). The proposal has been tested in experiments using a needle-to-plate electrode arrangement in air, and reproducible Trichel pulses (single or in a series) were obtained by triggering them with an appropriately designed voltage waveform. The proposed method and results obtained have been qualitatively analysed. The analysis provides guidance for designing the voltage ramp pulse in respect of the generation of a single Trichel pulse or a series of single Trichel pulses. The controlled generation of a single Trichel pulse or a series of such pulses would be a helpful research tool for the refined studies of the fundamental processes in a negative corona discharge in a single- (air is an example) and multi-phase gaseous fluids. The controlled generation of a single Trichel pulse or a series of Trichel pulses can also be attractive for those corona treatments which need manipulation of the electric charge and heat portions delivered by the Trichel pulses to the object.

  3. Correction of diagnostic x-ray spectra measured with CdTe and CdZnTe detectors

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, M [Osaka Univ., Suita (Japan). Medical School; Kanamori, H; Toragaito, T; Taniguchi, A

    1996-07-01

    We modified the formula of stripping procedure presented by E. Di. Castor et al. We added the Compton scattering and separated K{sub {alpha}} radiation of Cd and Te (23 and 27keV, respectively). Using the new stripping procedure diagnostic x-ray spectra (object 4mm-Al) of tube voltage 50kV to 100kV for CdTe and CdZnTe detectors are corrected with comparison of those spectra for the Ge detector. The corrected spectra for CdTe and CdZnTe detectors coincide with those for Ge detector at lower tube voltage than 70kV. But the corrected spectra at higher tube voltage than 70kV do not coincide with those for Ge detector. The reason is incomplete correction for full energy peak efficiencies of real CdTe and CdZnTe detectors. (J.P.N.)

  4. TeV gravity at neutrino telescopes

    International Nuclear Information System (INIS)

    Illana, J.I.; Masip, M.; Meloni, D.

    2005-01-01

    Cosmogenic neutrinos reach the Earth with energies around 10 9 GeV, and their interactions with matter will be measured in upcoming experiments (Auger, IceCube). Models with extra dimensions and the fundamental scale at the TeV could imply signals in these experiments. In particular, the production of microscopic black holes by cosmogenic neutrinos has been extensively studied in the literature. Here we make a complete analysis of gravity-mediated interactions at larger distances, where they can be calculated in the eikonal approximation. In these processes a neutrino of energy E ν interacts elastically with a parton inside a nucleon, loses a small fraction y of its energy, and starts a hadronic shower of energy yE ν ν . We analyze the ultraviolet dependence and the relevance of graviton emission in these processes, and show that they are negligible. We also study the energy distribution of cosmogenic events in AMANDA and IceCube and the possibility of multiple-bang events. For any neutrino flux, the observation of an enhanced rate of neutral current events above 100 TeV in neutrino telescopes could be explained by TeV-gravity interactions. The values of the fundamental scale of gravity that IceCube could reach are comparable to those to be explored at the LHC

  5. Coherent combining pulse bursts in time domain

    Science.gov (United States)

    Galvanauskas, Almantas

    2018-01-09

    A beam combining and pulse stacking technique is provided that enhances laser pulse energy by coherent stacking pulse bursts (i.e. non-periodic pulsed signals) in time domain. This energy enhancement is achieved by using various configurations of Fabry-Perot, Gires-Tournois and other types of resonant cavities, so that a multiple-pulse burst incident at either a single input or multiple inputs of the system produces an output with a solitary pulse, which contains the summed energy of the incident multiple pulses from all beams. This disclosure provides a substantial improvement over conventional coherent-combining methods in that it achieves very high pulse energies using a relatively small number of combined laser systems, thus providing with orders of magnitude reduction in system size, complexity, and cost compared to current combining approaches.

  6. Linear transformer driver for pulse generation

    Science.gov (United States)

    Kim, Alexander A; Mazarakis, Michael G; Sinebryukhov, Vadim A; Volkov, Sergey N; Kondratiev, Sergey S; Alexeenko, Vitaly M; Bayol, Frederic; Demol, Gauthier; Stygar, William A

    2015-04-07

    A linear transformer driver includes at least one ferrite ring positioned to accept a load. The linear transformer driver also includes a first power delivery module that includes a first charge storage devices and a first switch. The first power delivery module sends a first energy in the form of a first pulse to the load. The linear transformer driver also includes a second power delivery module including a second charge storage device and a second switch. The second power delivery module sends a second energy in the form of a second pulse to the load. The second pulse has a frequency that is approximately three times the frequency of the first pulse. The at least one ferrite ring is positioned to force the first pulse and the second pulse to the load by temporarily isolating the first pulse and the second pulse from an electrical ground.

  7. Pulse amplitude and frequency effects in a pulsed packed column

    International Nuclear Information System (INIS)

    Russell, S.H.

    1954-04-01

    A study has been made of the effect on the efficiency and capacity of applying pulses of varying amplitude and frequency to a packed column. In the efficiency studies, the maximum efficiency was obtained with a pulse having an amplitude of 3/8'' and a frequency of 140 cycles per minute. Under these conditions, the column was about five times as efficient as a simple packed column. Two general types of results were obtained in the capacity studies. Under certain conditions, the capacity increased over that of a simple packed column, but under others, it decreased. Some of the factors causing this were investigated but the fundamental reasons were not determined due to a lack of personnel for the necessary experiments. (author)

  8. Pulse amplitude and frequency effects in a pulsed packed column

    Energy Technology Data Exchange (ETDEWEB)

    Russell, S H

    1954-04-15

    A study has been made of the effect on the efficiency and capacity of applying pulses of varying amplitude and frequency to a packed column. In the efficiency studies, the maximum efficiency was obtained with a pulse having an amplitude of 3/8'' and a frequency of 140 cycles per minute. Under these conditions, the column was about five times as efficient as a simple packed column. Two general types of results were obtained in the capacity studies. Under certain conditions, the capacity increased over that of a simple packed column, but under others, it decreased. Some of the factors causing this were investigated but the fundamental reasons were not determined due to a lack of personnel for the necessary experiments. (author)

  9. Surface preparation effects on efficient indium-tin-oxide-CdTe and CdS-CdTe heterojunction solar cells

    Science.gov (United States)

    Werthen, J. G.; Fahrenbruch, A. L.; Bube, R. H.; Zesch, J. C.

    1983-05-01

    The effects of CdTe surface preparation and subsequent junction formation have been investigated through characterization of ITO/CdTe and CdS/CdTe heterojunction solar cells formed by electron beam evaporation of indium-tin-oxide (ITO) and CdS onto single crystal p-type CdTe. Surfaces investigated include air-cleaved (110) surfaces, bromine-in-methanol etched (110) and (111) surfaces, and teh latter surfaces subjected to a hydrogen heat treatment. Both air-cleaved and hydrogen heat treated surfaces have a stoichiometric Cd to Te ratio. The ITO/CdTe junction formation process involves an air heat treatment, which ahs serious effects on the behavior of junctions formed on these surfaces. Etched surfaces which have a large excesss of Te, are less affected by the junction formation process and result in ITO/CdTe heterojunctions with solar efficiencies of 9% (Vsc =20 mA/cm2). Use of low-doped CdTe results in junctions characterized by considerably larger open-circuit votages (Voc =0.81 V) which are attributable to increasing diode factors caused by a shift from interfacial recombination to recombination in the depletion region. Resulting solar efficiencies reach 10.5% which is the highest value reported to date for a genuine CdTe heterojunction, CdS/CdTe heterojunctions show a strong dependence on CdTe surface condition, but less influence on the junction formation process. Solar efficiencies of 7.5% on an etched and heat treated surface are observed. All of these ITO/CdTe and CdS/CdTe heterojunctions have been stable for at least 10 months.

  10. New chalcogenide glasses in the CdTe-AgI-As{sub 2}Te{sub 3} system

    Energy Technology Data Exchange (ETDEWEB)

    Kassem, M. [Univ. Picardie Jules Verne, F-80000 Amiens (France); Le Coq, D., E-mail: david.lecoq@univ-littoral.fr [Univ. Lille Nord de France, F-59000 Lille (France); ULCO, LPCA, EA 4493, F-59140 Dunkerque (France); Boidin, R.; Bychkov, E. [Univ. Lille Nord de France, F-59000 Lille (France); ULCO, LPCA, EA 4493, F-59140 Dunkerque (France)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Determination of the glass-forming region in the pseudo-ternary CdTe-AgI-As{sub 2}Te{sub 3} system. Black-Right-Pointing-Pointer Characterization of macroscopic properties of the new CdTe-AgI-As{sub 2}Te{sub 3} glasses. Black-Right-Pointing-Pointer Characterization of the total conductivity of CdTe-AgI-As{sub 2}Te{sub 3} glasses. Black-Right-Pointing-Pointer Comparison between the selenide and telluride equivalent systems. -- Abstract: Chalcogenide glasses in the pseudo-ternary CdTe-AgI-As{sub 2}Te{sub 3} system were synthesized and the glass-forming range was determined. The maximum content of CdTe in this glass system was found to be equal to 15 mol.%. The macroscopic characterizations of samples have consisted in Differential Scanning Calorimetry, density, and X-ray diffraction measurements. The cadmium telluride addition does not generate any significant change in the glass transition temperature but the resistance of binary AgI-As{sub 2}Te{sub 3} glasses towards crystallisation is estimated to be decreasing on the base of {Delta}T = T{sub x} - T{sub g} parameter. The total electrical conductivity {sigma} was measured by complex impedance spectroscopy. First, the CdTe additions in the (AgI){sub 0.5}(As{sub 2}Te{sub 3}){sub 0.5} host glass, (CdTe){sub x}(AgI){sub 0.5-x/2}(As{sub 2}Te{sub 3}){sub 0.5-x/2} lead to a conductivity decrease at x {<=} 0.05. Then, the behaviour is reversed at 0.05 {<=} x {<=} 0.15. The obtained results are discussed by comparison with the equivalent selenide system.

  11. Magnetic pulse sharpener and delay-line

    International Nuclear Information System (INIS)

    Li Jin; Dai Guangsen; Xia Liansheng

    2002-01-01

    This paper describes a method to achieve short rise time pulse which has been delayed with a delay-line and magnetic pulse sharpener. A delay-line and two shock-lines are designed to carry pulsed signal with a maximum voltage magnitude up to 80 kV. A pulse of High voltage with arise time of 48 ns at a level of 0.1%-0.9% were achieved, and the attenuation in the line is very small

  12. Pulse to pulse monitoring of the SLD detector

    International Nuclear Information System (INIS)

    Bogart, J.; Huffer, M.; Russell, J.

    1993-04-01

    The SLAC Linear Collider produces bunches of positrons and polarized electrons which collide at 120 hertz inside the SLD detector. A limited amount of information is collected for each pulse in the modules which do real-time data acquisition. Buffers of approximately ten seconds' worth of this monitor data are periodically delivered to a VAX. The generation and uses of the monitor data will be discussed

  13. Microstructural, nanomechanical, and microtribological properties of Pb thin films prepared by pulsed laser deposition and thermal evaporation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Broitman, Esteban, E-mail: esbro@ifm.liu.se [Thin Film Physics Division, IFM, Linköping University, SE-581 83 Linköping (Sweden); Flores-Ruiz, Francisco J. [Thin Film Physics Division, IFM, Linköping University, SE-581 83 Linköping, Sweden and Centro de Investigación y de Estudios Avanzados del I.P.N., Unidad Querétaro, Querétaro 76230 (Mexico); Di Giulio, Massimo [Università del Salento, Dipartimento di Matematica e Fisica “E. De Giorgi”, 73100 Lecce (Italy); Gontad, Francisco; Lorusso, Antonella; Perrone, Alessio [Università del Salento, Dipartimento di Matematica e Fisica “E. De Giorgi”, 73100 Lecce, Italy and INFN-Istituto Nazionale di Fisica Nucleare, 73100 Lecce (Italy)

    2016-03-15

    In this work, the authors compare the morphological, structural, nanomechanical, and microtribological properties of Pb films deposited by thermal evaporation (TE) and pulsed laser deposition (PLD) techniques onto Si (111) substrates. Films were investigated by scanning electron microscopy, surface probe microscopy, and x-ray diffraction in θ-2θ geometry to determine their morphology, root-mean-square (RMS) roughness, and microstructure, respectively. TE films showed a percolated morphology with densely packed fibrous grains while PLD films had a granular morphology with a columnar and tightly packed structure in accordance with the zone growth model of Thornton. Moreover, PLD films presented a more polycrystalline structure with respect to TE films, with RMS roughness of 14 and 10 nm, respectively. Hardness and elastic modulus vary from 2.1 to 0.8 GPa and from 14 to 10 GPa for PLD and TE films, respectively. A reciprocal friction test has shown that PLD films have lower friction coefficient and wear rate than TE films. Our study has demonstrated for first time that, at the microscale, Pb films do not show the same simple lubricious properties measured at the macroscale.

  14. Complementarity of long pulse and short pulse spallation sources

    Energy Technology Data Exchange (ETDEWEB)

    Mezei, F [Hahn-Meitner-Institut Berlin GmbH (Germany)

    1995-11-01

    The complementarity of short pulse spallation sources (SPSS) and steady state (CW) reactors is a widely accepted concept. SPSS and long pulse spallation sources (LPSS) are complementary in two ways: (a) in their performance in neutron scattering experiments LPSS closely emulate CW reactors. In this respect two facets of the time-of-flight (TOF) monochromator method adequate for LPSS will be discussed: the superiority of the TOF approach to the crystal monochromator method in high resolution powder diffraction, and the novel technique of repetition rate multiplication in TOF spectroscopy, (b) LPSS combined with adequate chopper systems can also emulate SPSS in a number of applications. It will be shown that the LPSS method of producing short neutron pulses is more efficient for cold and thermal neutrons (below an energy of about 100 MeV), while SPSS is the more favourable approach for hot, epithermal neutrons, i.e. in the slowing down regime in contrast to the moderated regime. These two aspects of complementarity of LPSS and SPSS lead to the conclusions that for about 75% of the spectrum of neutron scattering experiments as known of today the LPSS approach is the most advantageous one with a feasible neutron intensity exceeding that available at ILL by a factor of about 30, while for the remaining 25% of applications the SPSS technique is superior with a well-known potential of a similar gain over present day performances. (author) 7 figs., 6 refs.

  15. Complementarity of long pulse and short pulse spallation sources

    International Nuclear Information System (INIS)

    Mezei, F.

    1995-01-01

    The complementarity of short pulse spallation sources (SPSS) and steady state (CW) reactors is a widely accepted concept. SPSS and long pulse spallation sources (LPSS) are complementary in two ways: a) in their performance in neutron scattering experiments LPSS closely emulate CW reactors. In this respect two facets of the time-of-flight (TOF) monochromator method adequate for LPSS will be discussed: the superiority of the TOF approach to the crystal monochromator method in high resolution powder diffraction, and the novel technique of repetition rate multiplication in TOF spectroscopy, b) LPSS combined with adequate chopper systems can also emulate SPSS in a number of applications. It will be shown that the LPSS method of producing short neutron pulses is more efficient for cold and thermal neutrons (below an energy of about 100 MeV), while SPSS is the more favourable approach for hot, epithermal neutrons, i.e. in the slowing down regime in contrast to the moderated regime. These two aspects of complementarity of LPSS and SPSS lead to the conclusions that for about 75% of the spectrum of neutron scattering experiments as known of today the LPSS approach is the most advantageous one with a feasible neutron intensity exceeding that available at ILL by a factor of about 30, while for the remaining 25% of applications the SPSS technique is superior with a well-known potential of a similar gain over present day performances. (author) 7 figs., 6 refs

  16. New autocorrelation technique for the IR FEL optical pulse width measurements

    Energy Technology Data Exchange (ETDEWEB)

    Amirmadhi, F.; Brau, K.A.; Becker, C. [Vanderbilt Univ., Nashville, TN (United States)] [and others

    1995-12-31

    We have developed a new technique for the autocorrelation measurement of optical pulse width at the Vanderbilt University FEL center. This method is based on nonlinear absorption and transmission characteristics of semiconductors such as Ge, Te and InAs suitable for the wavelength range from 2 to over 6 microns. This approach, aside being simple and low cost, removes the phase matching condition that is generally required for the standard frequency doubling technique and covers a greater wavelength range per nonlinear material. In this paper we will describe the apparatus, explain the principal mechanism involved and compare data which have been acquired with both frequency doubling and two-photon absorption.

  17. Detection methods of pulsed X-rays for transmission tomography with a linear accelerator

    International Nuclear Information System (INIS)

    Glasser, F.

    1988-07-01

    Appropriate detection methods are studied for the development of a high energy tomograph using a linear accelerator for nondestructive testing of bulky objects. The aim is the selection of detectors adapted to a pulsed X-ray source and with a good behavior under X-ray radiations of several MeV. Performance of semiconductors (HgI 2 , Cl doped CdTe, GaAs, Bi 12 Ge0 20 ) and a scintillator (Bi 4 Ge 3 0 12 ) are examined. A prototype tomograph gave images that show the validity of detectors for analysis of medium size equipment such as a concrete drum of 60 cm in diameter [fr

  18. Manipulation of Squeezed Two-Phonon Bound States using Femtosecond Laser Pulses

    Directory of Open Access Journals (Sweden)

    Nakamura Kazutaka G.

    2013-03-01

    Full Text Available Two-phonon bound states have been excited exclusively in ZnTe(110 via impulsive stimulated second-order Raman scattering, essentially being squeezed states due to phase coherent excitation of two identical components anticorrelated in the wave vector. By using coherent control technique with a pair of femtosecond laser pulses, the manipulation of squeezed states has been demonstrated in which both the amplitude and lifetime of coherent oscillations of squeezed states are modulated, indicating the feasibility to control the quantum noise and the quantum nature of phonon squeezed states, respectively.

  19. Pulse sequence optimization for superparamagnetic iron oxide-enhaced MR imaging in the detection of hepatic VX2 tumors in rabbits

    International Nuclear Information System (INIS)

    Jang, Hyun Jung; Han, Joon Koo; Lee, Kyoung Ho; Kim, Se Hyung; Choi, Byung Ihn; Kim, Tae Kyoung

    2003-01-01

    The purpose of this experimental study was to determine the optimal pulse sequences for SPIO-enhanced MR imaging in the evaluation of multiple hepatic tumors. Twelve rabbits with multiple VX2 liver tumors underwent SPOI-enhanced MRI using the following nine pulse sequences: TSE T2-weighted imaging (T2W1), TSE proton density-weighted imaging(PDWI), and GRE T2*-weighted imaging (T2*W1) with seven different echo times (TE). Liver-lesion contrast-to-noise ratios (CNRs) were calculated, and images were also assessed qualitatively by two radiologists, who reached a consensus as to lesion conspicuity and imaging artifacts using a four-level scale. By means of pathologic correlation, the sensitivity and positive predictive value of each sequence was calculated. TSE T2W1 and long-TE (35 msec) FLASH T2*W1 showed the highest liver-lesion CNR. The best lesion conspicuity was seen at TSE T2W1 and medium-TE (12 msec) GRE T2*W1. Short TE GRE T2*W1 showed the least imaging artifacts. The four sequences which demonstrated the best sensitivity were medium-TE (12 msec), GRE T2*W1 (FLASH, 84%; FISP, 82%), TSE W2T1 (79%), and TSE PDWI (76%). All nine sequences showed overall high positive predictive value (86-97%), with no statistically significant difference (p>0.05). In terms of image quality and the detection of sensitivity, TSE T2W1 and medium TE (12 msec) GRE T2*W1 were the top two pulse sequences among the various sequences used for no SPIO-enhanced MRI. They are thus considered to be optimal sequences for evaluating multiple malignant hepatic tumors

  20. A Study of New Pulse Auscultation System

    Directory of Open Access Journals (Sweden)

    Ying-Yun Chen

    2015-04-01

    Full Text Available This study presents a new type of pulse auscultation system, which uses a condenser microphone to measure pulse sound waves on the wrist, captures the microphone signal for filtering, amplifies the useful signal and outputs it to an oscilloscope in analog form for waveform display and storage and delivers it to a computer to perform a Fast Fourier Transform (FFT and convert the pulse sound waveform into a heartbeat frequency. Furthermore, it also uses an audio signal amplifier to deliver the pulse sound by speaker. The study observed the principles of Traditional Chinese Medicine’s pulsing techniques, where pulse signals at places called “cun”, “guan” and “chi” of the left hand were measured during lifting (100 g, searching (125 g and pressing (150 g actions. Because the system collects the vibration sound caused by the pulse, the sensor itself is not affected by the applied pressure, unlike current pulse piezoelectric sensing instruments, therefore, under any kind of pulsing pressure, it displays pulse changes and waveforms with the same accuracy. We provide an acquired pulse and waveform signal suitable for Chinese Medicine practitioners’ objective pulse diagnosis, thus providing a scientific basis for this Traditional Chinese Medicine practice. This study also presents a novel circuit design using an active filtering method. An operational amplifier with its differential features eliminates the interference from external signals, including the instant high-frequency noise. In addition, the system has the advantages of simple circuitry, cheap cost and high precision.

  1. Perceptions of European stakeholders of pulse fishing

    NARCIS (Netherlands)

    Kraan, M.L.; Trapman, B.K.; Rasenberg, M.M.M.

    2015-01-01

    This research project examines the concerns and questions of European stakeholders about pulse fishing, in order to assess to what extent the knowledge agenda on pulse fishing covers these issues. To get a first impression of the concerns about pulse fishing, and to get an idea of the stakeholders

  2. Pulse height model for deuterated scintillation detectors

    International Nuclear Information System (INIS)

    Wang, Haitang; Enqvist, Andreas

    2015-01-01

    An analytical model of light pulse height distribution for finite deuterated scintillation detectors is created using the impulse approximation. Particularly, the energy distribution of a scattered neutron is calculated based on an existing collision probability scheme for general cylindrical shaped detectors considering double differential cross-sections. The light pulse height distribution is analytically and numerically calculated by convoluting collision sequences with the light output function for an EJ-315 detector from our measurements completed at Ohio University. The model provides a good description of collision histories capturing transferred neutron energy in deuterium-based scintillation materials. The resulting light pulse height distribution details pulse compositions and their corresponding contributions. It shows that probabilities of neutron collision with carbon and deuterium nuclei are comparable, however the light pulse amplitude due to collisions with carbon nuclei is small and mainly located at the lower region of the light pulse distribution axis. The model can explore those neutron interaction events that generate pulses near or below a threshold that would be imposed in measurements. A comparison is made between the light pulse height distributions given by the analytical model and measurements. It reveals a significant probability of a neutron generating a small light pulse due to collisions with carbon nuclei when compared to larger light pulse generated by collisions involving deuterium nuclei. This model is beneficial to understand responses of scintillation materials and pulse compositions, as well as nuclei information extraction from recorded pulses.

  3. A study of new pulse auscultation system.

    Science.gov (United States)

    Chen, Ying-Yun; Chang, Rong-Seng

    2015-04-14

    This study presents a new type of pulse auscultation system, which uses a condenser microphone to measure pulse sound waves on the wrist, captures the microphone signal for filtering, amplifies the useful signal and outputs it to an oscilloscope in analog form for waveform display and storage and delivers it to a computer to perform a Fast Fourier Transform (FFT) and convert the pulse sound waveform into a heartbeat frequency. Furthermore, it also uses an audio signal amplifier to deliver the pulse sound by speaker. The study observed the principles of Traditional Chinese Medicine's pulsing techniques, where pulse signals at places called "cun", "guan" and "chi" of the left hand were measured during lifting (100 g), searching (125 g) and pressing (150 g) actions. Because the system collects the vibration sound caused by the pulse, the sensor itself is not affected by the applied pressure, unlike current pulse piezoelectric sensing instruments, therefore, under any kind of pulsing pressure, it displays pulse changes and waveforms with the same accuracy. We provide an acquired pulse and waveform signal suitable for Chinese Medicine practitioners' objective pulse diagnosis, thus providing a scientific basis for this Traditional Chinese Medicine practice. This study also presents a novel circuit design using an active filtering method. An operational amplifier with its differential features eliminates the interference from external signals, including the instant high-frequency noise. In addition, the system has the advantages of simple circuitry, cheap cost and high precision.

  4. Third Harmonic Imaging using a Pulse Inversion

    DEFF Research Database (Denmark)

    Rasmussen, Joachim; Du, Yigang; Jensen, Jørgen Arendt

    2011-01-01

    The pulse inversion (PI) technique can be utilized to separate and enhance harmonic components of a waveform for tissue harmonic imaging. While most ultrasound systems can perform pulse inversion, only few image the 3rd harmonic component. PI pulse subtraction can isolate and enhance the 3rd...

  5. <3> OMEGA pulse-forming network

    CERN Multimedia

    1974-01-01

    Adjustement of the 3 W pulse-forming network of the SPS beam dumping system. When charged at 60 kV, this PFN gives 10 kA, 25 ms current pulses, with oscillations, superimposed on the pulse flat top, of an amplitude of +/- 1 Ka.

  6. Electromagnetic Pulse Coupling Analysis of Electronic Equipment

    OpenAIRE

    Hong Lei; Qingying LI

    2017-01-01

    High-intensity nuclear explosion caused by high-altitude nuclear electromagnetic pulse through the antenna, metal cables, holes and other channels, coupled with very high energy into the electronic device, and cause serious threats. In this paper, the mechanism, waveform, coupling path and damage effect of nuclear electromagnetic pulse is analyzed, and the coupling mechanism of nuclear electromagnetic pulse is studied.

  7. Experiments on sediment pulses in mountain rivers

    Science.gov (United States)

    Y. Cui; T. E. Lisle; J. E. Pizzuto; G. Parker

    1998-01-01

    Pulses of sediment can be introduced into mountain rivers from such mechanisms as debris flows, landslides and fans at tributary confluences. These processes can be natural or associated with the activities of humans, as in the case of a pulse created by sediment derived from timber harvest or the removal of a dam. How does the river digest these pulses?

  8. Slow light pulse propagation in dispersive media

    DEFF Research Database (Denmark)

    Nielsen, Torben Roland; Mørk, Jesper; Lavrinenko, Andrei

    2009-01-01

    broadening or break-up of the pulse may be observed. The transition from linear to nonlinear pulse propagation is quantified in terms of the spectral width of the pulse. To cite this article: T.R. Nielsen et al., C. R. Physique 10 (2009). (C) 2009 Academie des sciences. Published by Elsevier Masson SAS. All...... rights reserved....

  9. Giant pulses of pulsar radio emission

    OpenAIRE

    Kuzmin, A. D.

    2007-01-01

    Review report of giant pulses of pulsar radio emission, based on our detections of four new pulsars with giant pulses, and the comparative analysis of the previously known pulsars with giant pulses, including the Crab pulsar and millisecond pulsar PSR B1937+21.

  10. Reversible Resistance Switching Effect in Amorphous Ge1Sb4Te7 Thin Films without Phase Transformation

    International Nuclear Information System (INIS)

    Hua-Jun, Sun; Li-Song, Hou; Yi-Qun, Wu; Xiao-Dong, Tang

    2009-01-01

    We demonstrate a reversible resistance switching effect that does not rely on amorphous-crystalline phase transformation in a nanoscale capacitor-like cell using Ge 1 Sb 4 Te 7 films as the working material. The polarity and amplitude of the applied electric voltage switches the cell resistance between low- and high-resistance states, as revealed in the current-voltage characteristics of the film by conductive atomic force microscopy (CAFM). This reversible SET/RESET switching effect is induced by voltage pulses and their polarity. The change of electrical resistance due to the switching effect is approximately two orders of magnitude

  11. Optical spectroscopy and Fermi surface studies of BiTeCl and BiTeBr

    Science.gov (United States)

    Martin, Catalin; Suslov, A. V.; Buvaev, S.; Hebard, A. F.; Bugnon, Philippe; Berger, Helmuth; Magrez, Arnaud; Tanner, D. B.

    2014-03-01

    The observation of a large bulk Rashba effect in the non-centrosymmetric semiconductors BiTeX(X=Cl, Br, I) has stimulated the interest in these sys- tems, as promising candidates for studying spin related phenomena and for the realization of spin devices. Here we present a comparative study of the electronic properties of BiTeCl and BiTeBr, determined from temperature dependent infrared spectroscopy and Shubnikov-de Haas oscillations. In par- ticular, we compare the angle dependence of quantum oscillations between the two compounds and discuss possible differences between the topology of their Fermi surfaces. Supported by NSF Cooperative Agreement DMR-1157490 to the National High Magnetic Field Laboratory.

  12. Patterns of digital volume pulse waveform and pulse transit time in ...

    African Journals Online (AJOL)

    In this study the digital volume pulse wave and the pulse transit time of the thumb and big toe were analyzed in young and older subjects some of whom were hypertensive. We aimed to study the components and patterns of the pulse waveform and the pulse transit time and how they might change. Material and Methods: ...

  13. CW seeded optical parametric amplifier providing wavelength and pulse duration tunable nearly transform limited pulses.

    Science.gov (United States)

    Hädrich, S; Gottschall, T; Rothhardt, J; Limpert, J; Tünnermann, A

    2010-02-01

    An optical parametric amplifier that delivers nearly transform limited pulses is presented. The center wavelength of these pulses can be tuned between 993 nm and 1070 nm and, at the same time, the pulse duration is varied between 206 fs and 650 fs. At the shortest pulse duration the pulse energy was increased up to 7.2 microJ at 50 kHz repetition rate. Variation of the wavelength is achieved by applying a tunable cw seed while the pulse duration can be varied via altering the pump pulse duration. This scheme offers superior flexibility and scaling possibilities.

  14. Unsplit bipolar pulse forming line

    Science.gov (United States)

    Rhodes, Mark A [Pleasanton, CA

    2011-05-24

    A bipolar pulse forming transmission line module and system for linear induction accelerators having first, second, third, and fourth planar conductors which form a sequentially arranged interleaved stack having opposing first and second ends, with dielectric layers between the conductors. The first and second planar conductors are connected to each other at the first end, and the first and fourth planar conductors are connected to each other at the second end via a shorting plate. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short at the first end a high voltage from the third planar conductor to the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral. Improved access to the switch is enabled by an aperture through the shorting plate and the proximity of the aperture to the switch.

  15. Pulse Propagation on close conductors

    CERN Document Server

    Dieckmann, A

    2001-01-01

    The propagation and reflection of arbitrarily shaped pulses on non-dispersive parallel conductors of finite length with user defined cross section is simulated employing the discretized telegraph equation. The geometry of the system of conductors and the presence of dielectric material determine the capacities and inductances that enter the calculation. The values of these parameters are found using an iterative Laplace equation solving procedure and confirmed for certain calculable geometries including the line charge inside a box. The evolving pulses and the resulting crosstalk can be plotted at any instant and - in the Mathematica notebook version of this report - be looked at in an animation. As an example a differential pair of microstrips as used in the ATLAS vertex detector is analysed.

  16. Ultrarelativistic electromagnetic pulses in plasmas

    Science.gov (United States)

    Ashour-Abdalla, M.; Leboeuf, J. N.; Tajima, T.; Dawson, J. M.; Kennel, C. F.

    1981-01-01

    The physical processes of a linearly polarized electromagnetic pulse of highly relativistic amplitude in an underdense plasma accelerating particles to very high energies are studied through computer simulation. An electron-positron plasma is considered first. The maximum momenta achieved scale as the square of the wave amplitude. This acceleration stops when the bulk of the wave energy is converted to particle energy. The pulse leaves behind as a wake a vacuum region whose length scales as the amplitude of the wave. The results can be explained in terms of a snow plow or piston-like action of the radiation on the plasma. When a mass ratio other than unity is chosen and electrostatic effects begin to play a role, first the ion energy increases faster than the electron energy and then the electron energy catches up later, eventually reaching the same value.

  17. Pulsed power, ICF, and SDI

    International Nuclear Information System (INIS)

    Van Devender, J.P.

    1986-01-01

    Pulsed power technology has been developed over many years for nuclear weapon effects simulation, inertial fusion, and directed energy. Every four years there is a factor of ten increase in power available, and we are now near the 100 TW, couple of million joule (MJ) mark, according to the author. 100 TW is sufficient for studying physics relevant to Inertial Confinement Fusion (ICF) or the Strategic Defense Initiative (SDI). Pulsed power can be viewed as a basic technology for making electron beams, X-rays, and ion beams. Applications include ICF, plasmoid-directed energy weapons, and microwave weapons. The author presents a set of tentative requirements for an effective defense, a concept for deploying the defense, and a strategy for making the transition to a defense-dominated world

  18. Pulse Holography: Review Of Applications

    Science.gov (United States)

    Smigielski, Paul

    1990-04-01

    Pulse Holography includes studies concerning time-varying phase objects as well as time-varying reflective objects involving the use of pulse ruby- and YAG-lasers. The paper is divided in two parts. One part concerns the direct use of 3-1) images reconstructed from holograms, i.e. applications to particle size analysis, 3-I) velocity measurements, 3-I) cinematography ... The second part describes applications using holographic interferometry in laboratory or in an industrial environment, i.e. applications to fluid mechanics, vibration analysis, non-destructive testing ... Recent developments including interferornetric cineholography, fiber optics, measurement of non-interferometric displacements ... , are also described. The future of holography depends to a great extent on data processing and interpretation of informations contained in holograms or holographic intericrograms. Therefore, we give the state of art in this field in Europe illustrated with some industrial applications.

  19. Partially coherent isodiffracting pulsed beams

    Science.gov (United States)

    Koivurova, Matias; Ding, Chaoliang; Turunen, Jari; Pan, Liuzhan

    2018-02-01

    We investigate a class of isodiffracting pulsed beams, which are superpositions of transverse modes supported by spherical-mirror laser resonators. By employing modal weights that, for stationary light, produce a Gaussian Schell-model beam, we extend this standard model to pulsed beams. We first construct the two-frequency cross-spectral density function that characterizes the spatial coherence in the space-frequency domain. By assuming a power-exponential spectral profile, we then employ the generalized Wiener-Khintchine theorem for nonstationary light to derive the two-time mutual coherence function that describes the space-time coherence of the ensuing beams. The isodiffracting nature of the laser resonator modes permits all (paraxial-domain) calculations at any propagation distance to be performed analytically. Significant spatiotemporal coupling is revealed in subcycle, single-cycle, and few-cycle domains, where the partial spatial coherence also leads to reduced temporal coherence even though full spectral coherence is assumed.

  20. Sound Beams with Shockwave Pulses

    Science.gov (United States)

    Enflo, B. O.

    2000-11-01

    The beam equation for a sound beam in a diffusive medium, called the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation, has a class of solutions, which are power series in the transverse variable with the terms given by a solution of a generalized Burgers’ equation. A free parameter in this generalized Burgers’ equation can be chosen so that the equation describes an N-wave which does not decay. If the beam source has the form of a spherical cap, then a beam with a preserved shock can be prepared. This is done by satisfying an inequality containing the spherical radius, the N-wave pulse duration, the N-wave pulse amplitude, and the sound velocity in the fluid.